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UNIVERSITY 
OF    ILLINOIS 


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UNIVERSITY   OF   ILLINOIS. 

Agricultural  Experiment  Station, 


.   URBANA,  MARCH,  189*. 


BULLETIN  NO.   38. 


EXPERIMENTS  WITH  THE  MUSCARDINE  DISEASE  OF  THE  CHINCH- 
BUG,    AND    WITH    THE    TRAP    AND    BARRIER    METHOD    FOR 

THE  DESTRUCTION  OF  THAT  INSECT. 

The  history  of  chinch-bug  injury  in  Illinois  is  substantially  that  of 
a  succession  of  waves  of  increase  which  slowly  rise  to  a  highest  point 
and  then  rapidly  fall  away  to  insignificance,  the  rise  of  the  wave  usu- 
ally occupying  from  three  to  five  years  or  more,  and  its  recession  com- 
monly requiring  only  one  or  two.  The  year  1894  was  marked  by  the 
culmination  of  such  a  period  of  increase,  the  wave  of  destruction  reach- 
ing very  nearly  its  highest  recorded  point,  and  covering  a  large  part  of 
this  state  from  the  Ohio  River  to  the  northern  tier  of  counties.  It  also 
extended  beyond  our  borders  into  Missouri,  Kansas,  and  southeastern 
Iowa.  In  Illinois  it  was  rrfost  injurious  (i)  in  the  southern  and  south- 
central  part  of  the  state,  (2)  in  the  western-central  counties,  and  (3)  in 
a  few  counties  near  the  northern  boundary — being  practically  harmless 
or  nearly  so  only  in  the  eastern  part  of  central  and  north-central  Illinois. 

Complaints  of  serious  injury  and  appeals  for  aid  were  received  at 
this  office  during  the  year  from  six  hundred  and  ten*  towns  in  seventy- 
six  counties — a  number  not  previously  equaled  since  1887.  The 
greater  part  of  these  appeals  took  the  form  of  applications  for  material 
with  which  to  introduce  the  contagious  insect  diseases  into  infested 
fields.  While  the  results  of  our  previous  experimental  work  with  the 
principal  fungous  disease  of  the  chinch-bug  were  not  favorable  to  the 

*In  Bulletin  5  from  the  State  Entomologist's  office  this  number  was  incorrectly  given  as  five 
hundred. 

25 


26  BULLETIN    NO.    38. 

idea  that  it  would  be  found  to  have  any  considerable  value  as  a  means  of 
arresting  injury  by  the  chinch-bug  where  conditions  were  particularly 
favorable  to  the  multiplication  and  maintenance  of  that  insect,  I  was 
nevertheless  induced  to  undertake  to  supply  this  demand,  largely  by  the 
following  considerations: 

1.  Notwithstanding  our  previous  experience,  I  was  not  yet  pre- 
pared to  say  positively  that  the  contagious-disease  method  if  persistently 
followed  up  would  not  take  effect  in  very  many  cases  even  under  ordi- 
nary circumstances;  and  as  long  as  there  was  even  an  appreciable  chance 
that  the  farmers  might  thus  save  any  considerable  part  of  their  crops 
this  season  by  our  aid  it  seemed  to  me  that  they  were  entitled  to  the 
benefit  of  the  doubt  in  favor  of  this  procedure,  especially  as  the  expense 
of  a  general  distribution  would  be  at  most  a  trifle  compared  with  the 
great  interests  at  stake. 

2.  The  general  credit  which  this  method  has  received  through  the 
agricultural  papers  and  the  daily  press,  as  well  as  through  several  state 
official  publications,  and  the  firm  belief  which  very  many  of  our  farmers 
already  had  in  it,  made  it  seem   very  likely  that  nothing  would  satisfy 
them  except  a  chance  to  try  it. 

3.  I  was  fairly  well  assured,  as  a  result  of  our  own  field  observa- 
tions and  laboratory  experiments,  that  under  favorable  weather  condi- 
tions this  contagious  disease  might  do  an  immense  service  to  those  parts 
of  the  state  threatened  with   the  destruction  of  wheat  and  corn;  and 
as  we  could  not  foresee  the  weather  of  the  season,  I  thought  it  incum- 
bent on  me  to  take  measures  to  derive  the  greatest  possible  advantage 
from  weather  favorable  to  the  spread  of  the  disease,  if  such  weather 
should  follow. 

4.  I  wished,  finally,  to  see  for   myself  how  generally  and  accu- 
rately the  somewhat  complicated  directions  necessary  to  an  intelligent 
use  of  this  method  would  be  followed  out  by  the  average  farmer  when 
greatly  interested  in  the  result. 

The  demand  for  contagion  material  became  so  great  by  June  i 
that  it  was  evident  that  I  should  no  longer  be  able  to  meet  it  from  cur- 
rent appropriations  at  my  disposal  and  with  the  aid  of  my  usual  corps  of 
assistants.  I  consequently  suggested,  early  in  June,  to  the  authorities 
of  the  State  Agricultural  Experiment  Station,  at  Urbana,  the  idea  of 
providing  for  more  elaborate  experiments  in  the  field,  and  of  supplying 
a  limited  amount  of  tested  infection-  material  for  trial  by  farmers  them- 
selves. This  plan  of  experimentation  and  distribution  was  very 
promptly  taken  up  and  favorably  considered  by  the  executive  com- 
mittee of  the  Station  board,  and  I  was  authorized  to  spend  in  this  direc- 
tion not  to  exceed  $200  previous  to  the  meeting  of  the  board  June  i, 
and  subsequent  to  that  meeting  $250  more.  I  consequently  engaged 
the  necessary  assistants,  enlarged  our  facilities,  and  published  a  general 
notice  to  those  interested  of  my  willingness  to  receive  live  chinch-bugs 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  27 

and  to  return  infected  ones  in  their  place.  I  used  for  this  purpose  the 
Associated  Press,  June  5,  1894,  an(^  a^so  sent  out  June  7»  through  the 
Experiment  Station  office,  a  press  bulletin  on  "The  Chinch-bug  in 
Illinois."  This  offer  was  most  eagerly  accepted  by  a  very  large  num- 
ber of  farmers,  and  we  were  presently  very  nearly  overwhelmed — as 
were  also  the  local  express  offices  and  the  post  office — by  packages  of 
chinch-bugs  arriving  from  all  parts  of  the  state,  and  in  all  imaginable 
conditions. 

In  order  to  avail  myself  of  the  much  larger  experience  of  the  Kan- 
sas University  Station,  I  followed  precisely  at  first  the  infection  meth- 
ods there  in  use,  depending  upon  an  exposure  of  the  chinch-bugs  to 
insects  dead  with  the  disease  and  covered  with  the  characteristic  fungous 
growth;  and  to  make  assurance  doubly  sure  I  had  already  obtained  a 
supply  of  material  directly  from  the  Kansas  State  University,  although 
we  had  the  same  fungus  in  our  own  infection  boxes  at  the  time.  Not- 
withstanding the  great  enlargement  of  our  facilities,  and  the  continuous 
expert  attention  which  the  whole  subject  received,  especially  from  Mr. 
John  Marten,  who  has  had  principal  charge  of  our  disease  experiments 
for  four  years,  the  contagion  did  not  spread  rapidly  enough  in  our  boxes 
to  make  it  possible  to  meet  at  once  more  than  a  small  percentage  of  the 
demand.  I  found  later  that  a  part  of  this  slow  development  was  due  to 
a  difficulty  which  seems  not  to  have  been  previously  noticed  by  any  one 
here  or  elsewhere;  namely,  the  appearance  in  our  contagion  boxes  of 
swarms  of  minute  mites  which  fed  upon  the  fungus  as  fast  as  it  was 
developed. 

Next,  observing  that  the  thirteen-year  locusts  (Cicada  tredecim},  a 
brood  of  which  was  rapidly  disappearing,  had  many  of  them  died  with 
this  disease,  and  bore  a  profuse  growth  of  the  characteristic  fungus  in 
excellent  condition,  I  had  a  large  quantity  of  these  collected,  and  used 
these  dead  locusts  for  distribution,  accompanied  in  each  case  by  chinch- 
bugs  which  had  been  exposed  to  the  infection. 

Finally,  having  ascertained,  as  a  result  of  experiments  made  pre- 
viously and  also  at  the  time,  that  the  'cultivated  fungus  grown  upon  a 
mixture  of  corn  meal  and  beef  broth  was  apparently  as  effective  for  the 
destruction  of  chinch-bugs  as  that  obtained  from  the  insects  themselves, 
I  had  a  large  quantity  grown  artificially  on  this  material,  and  used  this 
also  for  distribution. 

By  these  methods  I  succeeded,  by  about  the  2oth  of  July,  in  sup- 
plying all  who  had  sent  requests  up  to  the  loth  of  that  month — 
a  little  over  two  thousand  for  the  season.  As  I  had  issued  a  second 
bulletin  June  30,  giving  notice  that  it  would  be  impossible  to  continue 
the  distribution  beyond  July  10,  I  considered  the  obligations  I  had 
assumed  thus  fulfilled,  and  this  work  was  brought  practically  to  an  end. 


28  BULLETIN    NO.    38.  [March, 

Each  lot  of  chinch-bugs,  living  and  dead,  was  accompanied  by  the 
following  circular  of  directions  for  their  utilization,  and  of  caution  against 
hasty  observation  and  inference: 

"DEAR  SIR:  I  send  you  by  this  mail  chinch-bugs  which  have  been  successfully 
exposed  to  the  white  fungus  disease  of  that  insect,  and  are  in  a  condition  to  convey  it 
to  others. 

"To  propagate  this  disease  in  your  field,  make  a  tight  shallow  wooden  box,  say, 
24x36x6  inches,  and  place  in  it  a  layer  of  dirt  half  an  inch  deep,  free  from  leaves  or 
other  rubbish.  Moisten  this  dirt  without  making  it  muddy,  and  then  put  in  a  thin 
layer  of  green  wheat  or  corn.  Scatter  the  dead  chinch-bugs  sent  you  over  the  bottom 
of  the  box,  and  shut  up  with  them  a  quantity  of  live  bugs  from  the  field — as  many  as 
can  well  move  about  in  the  box  without  being  anywhere  more  than  one  layer  deep. 
Fasten  the  cover  down  tight,  so  that  nothing  can  escape,  and  set  the  box  where  it 
will  be  protected  from  sun  and  wind.  A  cellar  or  a  basement  room  is  to  be  preferred. 

"Open  the  box  daily  and  moisten  its  sides  and  contents  (without  making  them 
muddy)  when  they  begin  to  get  dry,  and  also  change  the  food  as  that  in  the  box  be- 
comes yellow.  When  it  is  seen  that  the  white,  mouldy  bugs  are  becoming  more 
numerous,  probably  in  about  three  or  four  days,  take  a  part  of  the  bugs,  dead  and 
alive,  out  of  the  box,  putting  in  fresh  live  ones  to  take  their  places,  and  close  the  box 
as  before. 

'  'Those  taken  out  should  then  be  scattered  through  the  infested  field  where  the 
bugs  are  thickest — at  the  bases  of  the  leaves  in  the  corn  fields,  around  the  lower  ends 
of  the  stalks,  and  the  like.  Make  this  distribution,  by  preference,  in  the  evening, 
when  the  dew  is  on,  or,  still  better,  just  after  a  rain,  and  repeat  if  dry  weather  fol- 
lows. Continue  these  collections  and  distributions  as  above  through  the  whole  season, 
making  certain  each  time  chinch-bugs  are  taken  out  that  white  ones  are  left  in  the 
box;  and  when  winter  comes  put  all  the  dead  bugs  remaining  into  pill  boxes  for  use 
the  following  year. 

"Those  wishing  to  form  an  independent  judgment  of  the  practical  value  of  this 
method  of  dealing  with  chinch-bugs  should  take  into  account  the  following  facts: 

"i.  The  white  fungus  causing  insect  disease  requires  moisture  for  its  full  devel- 
opment, and  especially  for  the  formation  of  the  minute  "spores"  by  whose  dispersal 
the  disease  is  conveyed  from  one  insect  to  another.  In  times  of  severe  drought  it 
propagates  slowly  or  not  at  all. 

"2.  It  takes  effect  on  a  weakened  insect  more  readily  than  on  one  in  full  vigor; 
on  the  full  grown  chinch-bug  more  easily  than  on  the  young;  and  hence  most  easily  of 
all  on  spent  adults  which  have  already  laid  their  eggs  and  are  about  to  perish  by  the 
natural  termination  of  their  life  period. 

"3.  It  is  a  native  disease  of  the  chinch-bug  and  never  dies  out  entirely,  but  is 
likely  to  appear  spontaneously  over  a  large  extent  of  country  when  conditions  favor- 
able to  its  development  are  long  maintained. 

"4.  Two  generations  of  the  chinch-bug  appear  each  year,  and  when  each  of 
these  generations  matures,  the  adult  bugs  commonly  take  wing  and  scatter,  thus  dis- 
appearing largely  from  fields  or  parts  of  fields  heavily  infested  by  them.  Such  dis- 
persal has  often  been  mistaken  for  a  destruction  of  chinch-bugs  by  disease.  One 
generation  matures  shortly  after  wheat  harvest  and  the  other  in  late  summer  and  in 
the  fall. 

"5.  The  chinch-bug  sheds  its  skin  four  times  while  growing,  and  the  empty  skins 
left  by  it  are  often  mistaken  for  dead  bugs — a  mistake  which  has  sometimes  led  to  a  false 
conclusion  as  to  the  effect  of  these  infection  experiments.  The  cast  skins  never  bear 
wings,  as  the  insect  does  not  moult  after  its  wings  are  formed.  They  may  further  be 
readily  distinguished  from  the  dead  bugs  by  the  fact  that  when  pressed  between  the 
thumb-nails  they  are  readily  seen  to  be  empty  shells  without  contents. 


EXPERIMENTS    WITH    CHINCH-BUGS.  29 

"To  judge  intelligently  of  the  effect  of  any  attempt  to  introduce  disease,  the 
observer  should  examine  very  carefully,  in  advance,  the  field  in  which  the  experiment 
is  to  be  tried,  and  adjacent  fields  as  well,  to  see  whether  bugs  dead  with  the  white 
fungus  may  not  already  be  present.  If  the  disease  appears  at  the  point  where  the 
infected  chinch-bugs  are  placed,  he  should  repeat  this  general  examination,  and  make 
sure  that  the  disease  may  not  have  occurred  spontaneously  and  without  special  refer- 
ence to  his  experimental  introduction  of  it.  He  should  also  notice  whether  young 
bugs  (those  without  wings)  are  attacked  by  it,  as,  if  they  are  not,  it  is  quite  likely  it 
is  only  carrying  away  those  about  to  die  of  old  age.  On  the  other  hand,  it  should  be 
remembered  that  these  especially  susceptible  adult  bugs  may  afford  the  best  means  of 
securing  a  general  dissemination  of  the  fungus  in  the  fields,  where  it  may  lie  dormant 
for  a  considerable  time,  ready  to  spring  into  sudden  activity  when  favorable  weather 
conditions  appear. 

"Advantage  should  be  taken  of  every  considerable  shower,  and  especially  of 
every  long  rain,  to  scatter  the  diseased  bugs,  and  all  fields  under  observation  should 
be  thoroughly  inspected  some  two  or  three  days  thereafter." 

I  was  also  careful  in  every  published  statement  or  written  com- 
munication on  the  subject  to  warn  all  against  reliance  upon  this 
method  to  the  neglect  of  other  preventive  or  destructive  measures,  and 
emphasized  in  every  way  its  purely  experimental  character. 

In  the  meantime,  experiments,  carefully  planned  and  closely 
followed  up,  were  made  in  the  field  through  Mr.  Marten  and  Mr. 
Johnson,  both  assistants  of  the  office,  by  the  distribution,  in  wheat  and 
corn  fields,  of  fungus  cultures  and  of  chinch-bugs  dead  with  disease 
and  bearing  the  characteristic  fungus  in  a  fruiting  condition.  One  series 
of  such  experiments  was  made  on  the  University  Experiment  Station 
farm,  at ,  Urbana,  and  others  were  set  on  foot  at  several  points  in 
southern  Illinois,  each  being  followed  up  by  repeated  visits  made  to 
ascertain  the  result. 

The  opportunity  was  improved  during  these  visits  to  examine  also 
several  experiments  made  by  farmers  of  our  acquaintance  with  material 
obtained  from  the  office  under  such  conditions  and  management  as  to 
give  them  positive  value. 

Pressing  and  engrossing  as  was  the  series  of  field  operations  under- 
taken this  year,  our  experimental  work  was  not  confined  to  these,  but 
laboratory  experiments  directed  lo  special  ends  were  carried  on  during 
some  weeks  by  the  aid  of  Miss  Nettie  Ayers,  a  recent  assistant  in  the 
bacteriological  laboratory  of  the  University  of  Illinois.  Artificial 
cultures,  under  varying  conditions,  of  the  Sporotrichum  characteristic 
of  the  chinch-bug  disease,  and  of  another  species  of  parasitic  fungus 
obtained  from  a  correspondent,  were  made  by  Miss  Ayers,  and  the 
results  of  such  cultures  were  tested  upon  chinch-bugs,  living  and  dead, 
upon  cabbage  worms  both  living  and  dead,  and  upon  a  variety  of  other 
insects,  these  experiments  being  so  managed  that  the  conditions  under 
which  they  were  made  were  precisely  subject  to  our  control. 

In  addition  to  these  various  experiments  with  the  contagion  method, 
I  made  at  Urbana  this  summer  a  thorough  test  of  certain  measures 


30  BULLETIN    NO.    38. 

for  the  arrest  and  destruction  of  chinch-bugs  as  they  moved  from  wheat 
to  corn  in  early  June  and  July. 

The  entire  series,  for  1894,  of  these  experimental  studies  in  the 
laboratory  and  in  the  field  are  here  reported,  whether  made  under  the 
immediate  auspices  of  the  Agricultural  Experiment  Station,  or  as  a  part 
of  the  regular  work  of  the  State  Laboratory  of  Natural  History.  The 
detailed  description  of  experiments  here  given  is  preceded  by  an  outline 
of  their  arrangement  and  subordination,  showing  in  every  case  their 
connection  with  each  other  and  the  entire  history  of  the  material  used 
in  each  experiment,  and  also  by  a  classified  list  of  the  experiments,  in 
which  they  are  grouped  according  to  their  objects. 

I  now  propose  to  state  and  discuss  the  general  conclusions  to  be 
drawn  from  this  work,  with  such  references  to  individual  experiments  as 
will  enable  the  critical  reader  to  judge  of  the  character  and  weight  of 
the  evidence  upon  which  these  conclusions  rest. 

GENERAL  DISCUSSION  OF  RESULTS. 

The  more  important  results  of  the  season's  experiments  which  have 
an  economic  value  may  be  briefly  summarized  in  the  following  terms: 

1.  The  white  muscardine  will  not  spread  among  vigorous  chinch- 
bugs  in  the  field  in  very  dry  weather  to  an  extent  to  give  this  disease 
any  practical  value  as  a  means  of  promptly  arresting  serious  chinch-bug 
injury  under  such  conditions.     (See  Nos.  55  to  58,  and  61,  62,  77,  etc.) 
On  the  contrary,  even  when  it  has  appeared  spontaneously,  or  as  a  result 
of  artificial  measures  for  its  introduction,  it  may  be  completely  arrested 
by  dry   weather,  remaining    in    abeyance    at    least    until    the   weather 
changes.     (See  No.  53,  June  5  and  June  20;  No.  55,  June  7,  June  19, 
and  August  8;  No.  57,  concluding  discussion;  Nos.  60,  63-67,  etc.) 

2.  It  is  most  likely  to  "catch"  in  low  spots,  where  the  soil  is  kept 
somewhat  moist  by  dense  vegetation,  a  mat  of  fallen  herbage,  or  the 
like.     Shocks  of  corn,  especially  when  the  crop  is  cut  early,  furnish  ex- 
cellent places  for  the  development  of  this  disease.     (See  No.  55,  June 
20;  No.  57,  September  18,  19,  and  28;    and  Nos.  76  and  77.)     Indeed, 
the  presence  in  any  field,  of  spots  especially  favorable  to  the  growth 
of  the  Sporotrichum  infection  seemed,  according  to  our  observations, 
to    have   much    more  to   do    with   the  appearance    and    spread    of  the 
white  muscardine  among  chinch-bugs  than  even  the  most  persistent  dis- 
tribution of  dead  or  infected  specimens  in  the  absence  of  such  natural 
culture  beds — a  fact  which  contains  the  suggestion  of  a  new  method  for 
the  propagation  and  dissemination  of  this  disease.     It  will  be  well  worth 
while,  consequently,  to  try  the  effect  of  excessive  moisture  and  an  invit- 
ing shelter  on  here  and  there  a  spot  in  an  infested  field,  such  as  might 
be  afforded  by  an  overgrowth  of  small  grain  produced  by  heavy  fertili- 
zation; or  by  trampling  down  a  few  hills  of  corn;  or  by  the  early  cut- 
ting and  shocking  of  some  small  part  of  the  crop.     If   no  spontaneous 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  3! 

development  of  muscardine   were  to  follow,  such  spots  would  at  any 
rate  be  excellent  places  to  start  a  field  infection. 

3.  If  decidedly  wet  weather  follows  upon  its  introduction,  even 
after  an  interval  of  several  weeks,  it  is  likely  to  start  up  and  take  visible 
effect;  but  continuous  rains,  depressing  the  vital  energies  of  the  insect, 
seem  commonly  requisite  to  its  efficient  action.  (See  Nos.  55  to  58, 77,  etc.) 

4.  It  is  always  so  generally  prevalent,  in  a  more  or  less  obscure 
condition,  among  chinch-bugs  or  other  insects  in  Illinois,  both  north  and 
south,  that  it  is  very  likely  to  appear  and  spread,  as  if   spontaneously, 
whenever  conditions  favorable  to  its  development  long  prevail,  whether 
it  has  been  purposely  introduced  or  not.     (See  especially  No.  76.) 

5.  The  time  elapsing  between  the  establishment  of  such  favorable 
conditions  and  the  full  development  of  the  disease  among  the  chinch- 
bugs  of  any  locality,  may  possibly  be  shortened  if  the  infection  has  pre- 
viously been  introduced  by  artificial  means;  but  our  own  experiments, 
it  must  be  confessed,  do  not  lend  any   material  support  to  this  suppo- 
sition.    (See  No.  57,  concluding  discussion.) 

6.  Whatever  weakens  the  insect  favors  its  spread,  as  a  rule.     It  is- 
consequently  much  more  likely  to  attack  adults  than  young,  especially 
spent  males,  and  females  which  have  laid  their  eggs,  and  which  are  soon 
to  die  of  old   age;  but   it  nevertheless  often   kills  young  of  all  ages. 
From  the  record  of  our  large  contagion  boxes  (Nos.  68-71)  it  appears 
that  after  the  establishment   in   my  laboratory,   July   i,   of    a  special 
reception  box  into  which  all  insects  sent  in  by  mail  or  express  were  put 
as  received,  the  development  of  the  fungus  in  the  contagion  boxes  was 
much  less  rapid   than  before.     The  reception  box  was  so  managed  that 
not  only  were  all  dead  bugs  excluded  from  the  contagion  boxes,  but 
only  the  more  vigorous  of  those  remaining  alive  at  the   time  of  their 
arrival  were  transferred. 

The  supposed  weakening  effect  of  close  confinement  in  a  saturated 
atmosphere  was  also  avoided  in  this  reception  box  by  leaving  it  open, 
the  escape  of  the  bugs  being  prevented  by  heavily  chalking  the  inside 
of  the  box  for  four  or  five  inches  downward  from  the  top.  This  chalk- 
band  was  renewed  occasionally,  as  it  was  worn  away  by  the  chinch-bugs 
in  their  efforts  to  escape.  The  same  device  was  used  to  confine  the 
bugs  in  the  contagion  boxes  when  these  were  opened.  The  apparent 
effect  of  this  elimination  of  weakened  insects  was  greatly  to  diminish 
the  number  which  succumbed  to  the  muscardine  infection. 

In  agreement  with  the  above,  we  have  noticed  that  the  fall  genera- 
tion of  adults  is  less  subject  to  it,  other  things  being  equal,  than  the 
generation  which  matures  in  midsummer.  As  this  fall  brood  is  to  live 
over  winter  before  laying  its  eggs,  it  contains  no  worn  out  adults. 

7.  The  fungus  producing  this  disease  will  start  rarely,  if  at  all,  on 
dead  chinch-bugs,  if  we  may  judge  from  the  results  of  several  experi- 
ments made  this  summer  (see  Nos.  36-40  and  Nos.  46  and  47).      Where- 


32  BULLETIN  NO.  38.  [March, 

ever  a  dead  chinch-bug  shows  the  fungus  in  the  field,  it  is  therefore 
probable  that  it  was  infected  while  alive.  Some  doubt  is  thrown  upon 
this  conclusion,  however,  by  the  fact  that  upon  dead  soft-bodied  insects, 
like  cabbage  worms,  the  Sporotrichum  grew  as  promptly  and  luxuri- 
antly as  upon  the  insects  infected  while  still  alive.  (See  Nos.  21-27  an<* 
41.) 

8.  The  resistant  power  of  healthy  chinch-bugs  exposed  to  infec- 
tion is  well  shown  by  the  fact  that  thousands  of  bugs,  young  and  old, 
have  commonly   lived   for   many   days,  and    even    for    several  weeks, 
moulting,  maturing,  copulating,  and  laying  their  eggs,  when  shut  up  in 
contagion  boxes  which   had  been  heavily  stocked  with  fungus  spores 
from    dead    insects    and    had    been    made    in    every  way   as    favorable 
as  possible   to   the   development   of  the   disease.     The   percentage   of 
those    that  would    succumb    from    day  to  day   was    often    ridiculously 
small.     (See  Nos.  68-71.)     On  the  other  hand,  it  is  probable  that  the 
heavy  pressure  upon  the   office   for  a  supply   of   infected   chinch-bugs 
frequently  induced  the  too  early  and  complete   removal  of  the  bugs 
from  such  boxes,  thus  retarding  the  development  of  the  fungus  among 
the  imprisoned  insects. 

9.  The  growth  of  the  fungus  in  such  boxes  is  sometimes  checked 
and  the  whole  experiment  brought  to  a  standstill  by  the  appearance  in 
the  boxes  of  minute  mites  (apparently  brought  in  with  the  food  sup- 
plied to  the  bugs),  which  multiply  in  the  boxes  and  greedily  devour  the 
fungus  of  white  muscardine  as  fast  as  it  grows.      (See  No.  68,  July  31, 
August  9  and  22;    No.  69,  July  30  and   August  3;   No.  70,   July  30 
and  31,  and  August  2;  and  No.  71,  July  30.) 

These  mites  were  repeatedly  noticed  by  us  in  July,  but  were  not 
suspected  of  an  injurious  influence  on  our  operations  until  July  30, 
when  experiments  made  showed  us  that  they  were  diligently  feeding 
on  the  growing  Sporotrichum.  Confined  with  a  fungus -covered  chinch- 
bug  July  30  at  3  P.  M.,  they  had  completely  cleared  it  off  by  the 
next  morning.  Another  lot,  placed  under  a  glass  with  four  such  bugs 
at  9  A.  M.,  had  eaten  up  the  last  vestige  of  the  fungus  by  4:30  P.  M. 
Similar  trials  showed  that  they  would  clear  away  with  equal  readiness 
the  fungus  growth  from  a  culture  on  corn  meal  batter.  Prolonged 
search  of  the  earth  outside,  made  where  the  supply  for  our  contagion 
boxes  was  obtained,  and  a  similar  search  of  the  sources  of  the  food  sup- 
ply of  the  imprisoned  chinch-bugs,  gave  us  no  hint  of  the  origin  of  the 
mites.  The  same  mite  species  was  noticed  August  7  in  the  conta- 
gion box  of  a  farmer  near  Tonti,  in  southern  Illinois,  and  it  seems  likely 
that  these  mites  came  in  with  the  chinch-bugs  sent  us  from  the  field. 

10.  Comparative   experiments  with   fungus   spores   from  diseased 
chinch-bugs  and  with  those  derived  from  artificial  cultures  on  corn  meal 
moistened  with  beef  broth,  show  that  the  latter  are  nearly,  if  not  quite, 
as  efficient  agents  of  infection  as  the  former.     We  have  used  only  culti- 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  33 

vated  spores  two  or  three  removes  from  the  growth  on  the  insect,  and 
consequently  are  not  prepared  to  say  that  continued  cultivation  on  an 
inanimate  medium  might  not  finally  diminish  the  virulence  of  the 
fungus  parasite;  but,  on  the  other  hand,  we  have  no  very  good  reason  to 
suppose  that  this  will  prove  to  be  the  case;  and  I  have  no  doubt  that  by 
a  properly  guarded  procedure,  these  artificial  cultures,  which  can  easily 
be  made  in  almost  unlimited  quantity,  may  be  utilized  for  a  dissemina- 
tion of  the  spores  of  these  insect  diseases,  with  great  advantage  in 
convenience,  expedition,  and  economy  of  operation.  (Compare  Nos.  3, 
4,  and  5  with  No.  54;  also  No.  71  with  No.  70,  up  to  July  6.) 

Comparative  infection  experiments  with  acid  and  neutral  cultures 
were  indeterminate  in  result,  with  the  probability  favoring  the  greater 
efficiency  of  the  neutral  cultures.  (See  Nos.  15-20,  28,  and  51.) 

11.  The   history  of   Experiment  No.  i  and  its  derivatives  shows 
beyond  question  the  possibility  of  doing  excellent  work  on  chinch-bugs 
with  fungus  of  this  disease  derived    from   other   insect   species.     It  is 
probable   that    many   cases  of    its   apparently    spontaneous    appearance 
among  chinch-bugs  are  to  be  traced  to  such  sources  of  infection.     It 
was  upon  this  ground  that  fragments  of  thirteen-year  locusts  profusely 
covered  with  Sporotrichum  were  distributed  this  summer,  together  with 
chinch-bugs   previously  exposed  to  infection,   for  experimental  use  by 
farmers. 

12.  A  comparison  of  the  infection  experiments  made  on  chinch- 
bugs  with  those  made  on  cabbage  worms  shows  clearly  the  very  much 
greater  susceptibility  of  the  latter  to  Sporotrichum  attack — a  fact  due 
possibly  to  their  thinner  skin  and  more  juicy   substance.     Living  and 
dead    cabbage   worms  were    infected    with   equal    readiness  if  the  air 
was    kept    moist.      The    spores   started    quickly    on    any    part    of    the 
body,    the  growing  hyphae   penetrating    the  skin    in  one   place  seem- 
ingly as  freely  as  in  another.     An  external  development  of  the  fungus 
commonly   became  noticeable  on  the  second    day,    as  in  artificial   cul- 
tures.    Cabbage  worms  were  frequently,  but  not  invariably,  turned  a 
dull   red   color  by  the   growth  of    the  Sporotrichum.     In   one  experi- 
ment, which  differed  from  the  others  by  the  omission  of  the  layer  of 
moist  sand  on  the  bottom  of  the  dish  in  which  the  larvae  were  confined, 
this  raspberry  color  was  the  only  external  evidence  of  successful  infec- 
tion  with   the    Sporotrichum,   no   external    growth    appearing — a  fact 
probably  to  be  attributed  to  the  comparative  dryness  of  the  air. 

13.  This  is  the  place  to  make  mention  of  certain  experiments  with 
the  infection  of  insects  in  the  laboratory  which  resulted  in  unusual  devel- 
opments of  Sporotrichumglobuliferum,  illustrated  by  figures  accompany  ing 
this  report  (Plate  VII).      With  the  exception  of  the  two  growths  from 
June  beetles  (Fig.  5  and  6),   whose  botanical  characters  are  identical 
with  those   of    Sporotrichum,  these  figures  were  made  from  growths 
resulting  from  the  infection  of  living  insects  with  spores  from  cultures 


34  BULLETIN    NO.    38.  \_Mdrch, 

made  by  us.     The  identity  of  these  Isaria  forms  was  further  verified  by 
raising  the  common  Botrytis  form  from  them  on  agar. 

In  addition  to  the  above  .general  summary,  a  fuller  discussion  of 
experimental  methods  and  results  will  be  found  useful  for  the  special 
student  of  this  subject. 


EXPERIMENTAL    METHODS. 

Cultures  of  Sporotrichum. — All  our  culture  experiments  were 
made  by  the  strict  methods  of  the  bacteriological  laboratory,  preliminary 
sterilization  of  the  medium  on  which  the  fungus  was  grown  and  sub- 
sequent protection  of  the  culture  from  bacterial  invasion  having  been 
found  necessary  by  experiments  made  in  1891.  The  media  were  either 
peptonized  agar-agar,  or  a  batter  of  raw  corn  meal  made  up  with  beef 
broth  or  other  nutrient  fluid  prepared  according  to  the  customary  pro- 
cedure of  the  bacteriologist. 

A  few  new  experiments  were  made,  additional  to  those  of  previous 
years,  with  variations  in  the  culture  medium,  especially  by  acidulating 
it,  and  some  preliminary  trials  were  begun  to  determine  the  effect  of 
variations  in  the  temperature  at  which  the  cultures  were  kept.* 

The  apparatus  used  by  us  was  in  all  cases  either  the  common  test- 
tube  with  a  cotton  plug,  or  a  glass  fruit  jar  of  the  "  Mason  "  pattern 
(usually  of  a  capacity  of  two  quarts),  the  metal  cap  of  which  screws 
on  to  the  top  of  the  jar  with  a  flat  rubber  ring  intervening.  The  caps 
were  altered  by  closely  soldering  a  tin  tube  into  an  opening  in  the  top 
of  each  (see  Plate  V.,  Fig.  i),  as  a  safeguard  against  accidental  infection 
by  bacteria  when  the  spores  were  sown  upon  the  medium,  and  also  for 
the  purpose  of  convenient  plugging  with  cotton  as  a  subsequent 
protection. 

In  charging  this  jar  with  the  culture  medium,  the  metal  cap  was 
removed  and  the  jar  was  partly  filled  with  the  corn-meal  batter,  mixed 
barely  thick  enough  to  settle  smoothly,  and  was  then  placed  upon  its 
side,  so  that  the  mixture  collecting  at  the  lower  part  of  the  jar  might 
present  as  large  a  surface  as  possible  for  the  growth  of  the  fungus. 
This  culture  jar  worked  very  satisfactorily,  any  secondary  infection  of 
the  culture  rarely  interfering  with  the  growth  and  complete  develop- 
ment of  the  Sporotrichum. 

The  cover  of  the  jar  was  of  course  removed  to  get  access  to  its 
contents,  and  if  it  was  desired  to  preserve  the  culture  for  some  time 
without  deterioration  the  jars  were  left  open  until  the  contents  were 
dried  out.  (See  Plate  VI.)  It  was  found  that  such  dried  masses  of 


*Experiments  of  this  description  are  much  to  be  desired,  so  conducted  as  to  determine  the 
temperature  optimum  of  Sporotrichwn  globuliferum,  as  well  as  the  limits  of  cold  and  heat  at 
which  growth  and  spore  formation  come  to  a  stand  and  at  which  the  fungus  itself,  or  its  spores, 
may  be  destroyed.  Similar  experiments  should  be  tried  with  the  effects  of  various  degrees  of  moisture. 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  35 

corn  meal  with  surfaces  covered  by  Sporotrichum  growths  could  be 
readily  and  successfully  freshened  and  revived  after  some  months  by 
simply  moistening  the  mass. 

The  various  experimental  cultures  of  the  season  were  greatly  inter- 
fered with  by  the  pressure  of  more  practical  operations,  and  little  was 
added  to  our  previous  knowledge  of  the  subject.  The  growths  on 
peptonized  agar  were  invariably  prompt  and  profuse,  excepting  where 
the  medium  was  too  highly  acid,  or  where  the  temperature  approxi- 
mated 100°  Fah.  (See  Nos.  29-35  and  48-50.)  Growth  from  the  spores 
at  ordinary  temperatures  was  commonly  noticeable  by  the  second  day ; 
sometimes  not  until  the  third.  Heads  of  spores  were  visibly  formed  on 
the  fifth  or  sixth  day,  and  were  ripe  on  the  eighth  day,  at  the  earliest. 
It  was  found  that  the  fungus  grew  more  profusely  and  luxuriantly  on 
an  acidulated  medium  than  on  an  alkaline  or  neutral  one.  (No.  29,  etc.) 
A  mixture  of  raw  corn  meal  with  water  in  which  potatoes  had  been 
boiled  was  apparently  better  adapted  for  the  culture  of  Sporotrichum 
than  the  batter  of  corn  meal  and  beef  broth,  but  this  conclusion  requires 
verification.  The  growth  on  these  corn-meal  mixtures  was  always  at 
least  as  prompt  and  generous  as  on  the  agar  gelatine. 

Chinch-bugs  in  Boxes. — In  our  experiments  with  the  transfer  of 
muscardine  to  healthy  chinch- bugs  by  enclosing  them  with  specimens 
dead  with  disease  in  especially  prepared  boxes,  we  found  that  a  layer  of 
moist  earth  in  the  bottom  of  the  box  was  an  important  aid  to  success,  and 
that  garden  soil  was  better  than  sand.  We  had  also  abundant  evidence 
that  these  experiments  were  most  successful  with  weakened  insects,  and 
especially  with  those  brought  in  from  the  field  after  the  older  genera- 
tion present  had  passed  its  reproductive  period  and  was  consequently 
about  to  die.  On  the  other  hand,  adults  in  coitu  were  occasionally  found, 
one  or  both  of  which  had  died  of  muscardine. 

Owing  to  unskilled  methods  of  preparation  and  packing,  and  like- 
wise to  delays  in  transit,  a  large  part  of  the  material  sent  to  the  office 
was  either  dead  when  received  or  in  a  badly  damaged  condition.  Al- 
though the  worst  of  this  material  was  always  rejected,  dead  bugs  ac- 
cumulated so  rapidly  in  our  contagion  boxes  as  to  foul  the  contents,  and 
to  breed  numerous  blow-fly  larvae  and  masses  of  Anguillulidae,  and  thus 
practically  to  interrupt  the  growth  of  the  Sporotrichum.  To  avoid  these 
disadvantages  large  reception  boxes  were  prepared,  each  provided  with 
a  second  bottom  of  coarse  slats,  a  few  inches  above  the  first.  The 
chinch-bugs  received  were  placed  on  the  lower  bottom,  and  the  vegeta- 
tion used  for  food  was  laid  upon  the  slats.  When  additions  were  to 
be  made  to  the  contagion  boxes  the  stalks  of  corn  and  other  food  were 
taken  out  and  beaten  and  shaken  over  the  boxes,  only  the  stronger  and 
better-fed  insects  being  thus  transferred.  While  this  procedure  had  the 
effect  to  eliminate  the  difficulties  due  to  dead  and  rotting  insects,  it  also 
brought  the  fungus  development  practically  to  a  stand,  and  it  was  not 


36  BULLETIN  NO.  38.  [March, 

until  these  more  hardy  chinch-bugs  had  been  kept  in  confinement  for 
some  weeks  that  they  began  to  suffer  noticeably  from  muscardine. 

The  difficulties  due  to  the  appearance  of  mites  in  the  infection 
boxes  have  already  been  referred  to.  Minute  Anguillulidae,  so  abun- 
dant among  dead  chinch-bugs  as  to  form  gray  patches  here  and  there, 
did  not  seem  to  affect  the  fungus  growth,  neither  were  the  blow-fly 
maggots  especially  injurious  to  these  cultures  so  far  as  we  could  observe. 
On  the  other  hand,  as  both  these  forms  devoured  dead  chinch-bugs  in- 
discriminately, they  doubtless  interfered  with  the  development  of  the 
fungus  in  the  boxes. 


CLASSIFIED    LIST   OF    EXPERIMENTS,   1894. 

Nos.  1-91.* 
CULTURES  ON  AGAR-AGAR. 

No.     i,  April  21.  Neutral  culture  from  dead  insect  larva. 

No.    6,  June  28.  Neutral  culture  from  No.  i. 

No.  u,  July     2.  Neutral  culture  from  No.  i. 

Nos.  29-35,  Aug.  2.     Acid  cultures  from  No.  n. 

No.  43,  July    3.  Neutral  culture  from  No.  i. 

No.  48,  July  27.  Neutral  culture  from  No.  43.    Temperature  test. 

No.  49,  July  30.  Neutral  culture  from  No.  43.    Temperature  test. 

No.  50,  July  27.  Neutral  culture  from  No.  43.    Temperature  test. 

CULTURES  ON  CORN-MEAL  MIXTURES. 

No.  2,  May  7.     Neutral  culture  in  fruit  jar.     From  No.  i. 

No.  7,  July  6.     Neutral  culture    on  corn  meal  and  agar  gelatine. 

From  No.  6. 
No.  8,  July  6.     Neutral  culture  on  corn  meal  and  potato  water. 

From  No.  6. 
No.  9,  July  6.     Neutral    culture   on    corn    meal    and   beef   broth. 

From  No.  6. 

No.  10,  July    9.     Acid  culture  from  No.  i. 
No.  12,  July  13.     Neutral  culture  in  fruit  jar.     From  No.  n. 
No.  13,  July  13.     Acid  culture  in  fruit  jar.     From  No.  n. 
No.  14,  July  17.     Acid  culture  in  fruit  jar.     From  No.  n. 
No.  42,  July    3.     Neutral  culture  in  fruit  jar.     From  No.  i. 
Nos.  44  and  45,  July  20.     Acid  culture  in  fruit  jar.     From  No.  43. 


*These  numbers  correspond  to  those  of  the  descriptions  of  experiments  following. 


1895-]  EXPERIMENTS  WITH  CHINCH-BUGS.  37 

CONTAGION  AND  INFECTION  EXPERIMENTS  WITH  LIVING  CHINCH- 
BUGS  IN  BOXES. 

No.  3,  May  n.     From  agar  culture  No.  i. 

No.  4,  May  16.     From  agar  culture  No.  i. 

No.  5,  May  17.     From  agar  culture  No.  i. 

No.  54,  May  25.     First  contagion  box.     Kansas  chinch-bugs. 

No.  56,  June  7.     Farmers'  contagion    box,  G.  C.  Wells.     From 

No.  54. 
No.  68,  June  22.     First  large  laboratory  contagion  box.     From 

No.  54. 
No.  69,  June  23.    Second  large  laboratory  contagion  box.     From 

No.  54. 
No.  70,  June  27.     Third  large  laboratory  contagion   box.     From 

No.  69. 
No.  71,  June  28.     Fourth  large  laboratory  contagion  box.     From 

No.  2. 

LABORATORY  INFECTION  EXPERIMENTS  WITH  LIVING 
CATERPILLARS. 

Cabbage  worms  (Pieris  rapae). 

Nos.  15  and  16,  July  31.     From  acid  corn-meal  culture  No.  14. 

Nos.  18-20,  July  28.     From  neutral  agar  culture  No.  n. 

No.  28,  July  31.     (Pupa.)     From  neutral  agar  culture  No.  n. 

No.  51,  July  27.     From  neutral  agar  culture  No.  43. 
Elm-leaf  caterpillar. 

No.  17,  July  28.     Infected  from  neutral  agar  culture  No.  n. 

LABORATORY  INFECTION  EXPERIMENTS  WITH  DEAD  INSECTS. 

Chinch-bugs. 

Nos.  36-40,  Aug.  2.     From  neutral  agar  culture  No.  n. 

Nos.  46  and  47,  July  20.     From  neutral  agar  culture  No.  43. 
Cabbage  worms. 

Nos.  21-24,  July  30.     From  neutral  agar  culture  No.  n. 

Nos.  25-27,  July  31.     From  neutral  agar  culture  No.  n. 

No.  41,  Aug.  2.     From  neutral  agar  culture  No.  11. 
Sphinx  larva. 

No.  52,  Aug.  2.     From  neutral  agar  culture  No.  43. 

FIELD  EXPERIMENTS  WITH  MUSCARDINE  FUNGUS. 

No.  53,  April  20.     Hollenbeck  farm,  near  Tonti. 
Nos.  55  and  56,  June  7.     Wells  farm,  near  Farina.     From  con- 
tagion box  No.  54. 


38  BULLETIN  NO.    38.  [March 

Nos.  57  and  58,  June  10.      Wells  farm,  near  Farina.     From   con- 
tagion box  No.  56. 
No.  59,  June  7.     Smith  farm,  near  Farina.     From  contagion  box 

No.  54. 
No.  60,  June  15.     Smith  farm,  near  Farina.     From  contagion  box 

No.  59. 

No.  6 1,  June  15.  University  farm.  From  contagion  box  No.  54. 
No.  62,  June  18.  University  farm.  From  contagion  box  No.  54. 
No.  63,  June  19.  Bartley  farm,  near  Edgewood.  From  contagion 

box  No.  54. 
Nos.  64  and  65,  Aug.  6.     Bartley  farm,  near  Edgewood.     From 

corn-meal  culture  No.  2  and  contagion  box  No.  68. 
No.  66,  Sept.  4.     Bartley  farm,  near  Edgewood.     From  contagion 

box  No.  68. 
No.  73,  Aug.  7.    Ferguson  farm,  near  Odin.    From  contagion  box 

No.  68. 
No.  74,  Aug.  7.    Silver  farm,  near  Odin.    From  corn-meal  culture 

No.  2. 
No.   75,  Aug.  7.     Robinson  farm,  near  Odin.     FronT  corn-meal 

culture  No.  2. 
No.  77,  May  15  and  June  10.    Heth  farm,  near  Edgewood.    From 

contagion  box  No.  54. 
No.  78,  June  25.     Wilson  farm,  near  Greenup.     From  contagion 

box  No.  54. 
No.  79,  July  i.     Jackson  farm,  near  Greenville.     From  contagion 

box  No.  54. 
No.  80,  June  20.     Filson  farm,  near  Xenia.     From  contagion  box 

No.  54. 

SPONTANEOUS  OUTBREAK  OF  MUSCARDINE. 

No.  76,  Oct.  6.     Hurd  farm,  near  Odin. 

See  also  No.  53,  June  5;  No.  55,  June  7  and  June  19;  No.  57,  con- 
cluding discussion;  No.  60,  June  19;  Nos.  63-67,  etc. 

EFFECT  OF  MOISTURE  ON  CHINCH-BUGS. 
No.  73,  June  i.     Bugs  confined  in  saturated  air. 

EXPERIMENTS  WITH   BARRIERS   AND   TRAPS. 

No.  8 1,  July  10.     University  farm,  furrow  experiment. 

No.  82,  July  ii.  University  farm,  furrow  and  post-hole  exp«ri- 
ment. 

No.  83,  July  12.  University  farm,  furrow  and  post-hole  experi- 
ment. 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  39 

No.  84,  July  12.  University  farm,  coal-tar  and  post-hole  experi- 
ment. 

No.  85,  July  13.  University  farm,  coal-tar  and  post-hole  experi- 
ment. 

No.  86,  July  10.  University  farm,  furrow,  coal-tar,  and  post-hole 
experiment. 

No.  87,  June  27.  Bartley  farm,  near  Edgewood,  field  furrow  ex- 
periment. 

No.  88,  June  28.  Smith  farm,  near  Farina,  furrow  and  log  ex- 
periment. 

No.  89,  June  15.  Filson  farm,  near  Xenia,  furrow,  post-hole,  and 
kerosene  emulsion  experiment. 

No.  90,  June  23.     Mayo,  near  Falmouth,  furrow  experiment. 

No.  91,  June  25.  Wilson  farm,  near  Greenup,  furrow  and  log 
experiment. 

OUTLINE  OF  EXPERIMENTS  WITH  CHINCH-BUG  MUS- 
CARDINE  FUNGUS  (Sporotrichum  globuliferum,  Speg. ). 

Nos.  i -80,* 
APRIL  21  TO  OCTOBER  10,  1894. 

No.  I,  April  21,  agar  culture,  from  dead  insect  larva. 
No.  2,  May  7,  neutral  corn-meal  culture  in  fruit  jars. 

No.  64,  August  6,  field  experiment,  Bartley  farm.  (See  also  under 
68.) 

No.  65,  August  6,  field  experiment,  Bartley  farm.  (See  also  under 
68.) 

No.  67,  September  7,  field  experiment,  Bartley  farm. 

No.  71?  June  28,  large  contagion  box  in  laboratory. 

No.  74,  August  7,  field  experiment,  Silver  farm. 

No.  75,  August  7,  field  experiment,  Robinson  farm. 
No.  3,  May  n,  laboratory  infection  experiment  with  chinch-bugs. 
No.  4,' May  1 6,  laboratory  infection  experiment  with  chinch-bugs. 
No.  5,  May  17,  laboratory  infection  experiment  with  chinch-bugs. 
No.  6,  June  28,  agar  culture. 

No.  7,  July  6,  test-tube  culture  on  corn  meal  and  agar  gelatine. 

No.  8,  July  6,  test-tube  culture  on  corn  meal  and  potato  water. 

No.  9,  July  6,  test-tube  culture  on  corn  meal  and  beef  broth. 
No.  10,  July  9,  culture  on  acidulated  corn-meal  batter. 
No.  n,  July  2,  agar  culture  in  twelve  test-tubes. 

*The  subordination  and  dependence  of  these  experiments,  one  upon  another,  is  indicated  by 
the  indentation  of  the  items  on  this  list.  For  example,  all  the  material  for  the  first  fifty-two  numbers 
was  derived,  directly  or  indirectly,  from  the  dead  insect  larva  referred  to  under  No.  i;  experiments 
64.  65,  etc.,  down  to  75,  were  begun  with  Sporotrichum  grown  as  stated  under  No. 2;  the  cabbage 
worms  mentioned  under  Nos.  15  and  16  were  infected  from  the  acid  culture  No.  14,  itself  the  third 
remove  from  the  dead  insect— and  so  on  through  the  list.  The  numbers  in  this  outline  correspond, 
of  course,  to  those  used  in  the  full  description  of  experiments  next  following.  It  should  be  noted, 
however,  that  No.  72  and  the  barrier  experiments,  Nos.  81  to  91,  are  not  represented  in  this  list. 


40  BULLETIN  NO.  38.  \March, 

No.  12,  July  13,  fruit-jar  cultures  on  neutral  corn-meal  batter. 

No.  13,  July  13,  fruit-jar  cultures  on  acidulated  corn-meal  batter. 

No.  14,  July  17,  fruit- jar  cultures  on  acidulated  corn-meal  batter. 
No.  15,  July  31,  infection  experiment  with  live  cabbage  worms. 
No.  1 6,  July  31,  infection  experiment  with  live  cabbage  worms. 

No.  17,  July  28,  infection  experiment  with  elm-leaf  caterpillar. 

Nos.  18-20,  July  28,  infection  experiments  with  live  cabbage  worms. 

Nos.  2 1-24,  July  30,  infection  experiments  with  dead  cabbage  worms. 

Nos.  25-27,  July  3 1 ,  infection  experiments  with  dead  cabbage  worms. 

No.  28,  July  31,  infection  experiment  with  pupae  of  cabbage  worms. 

Nos.  29-35,  Aug.  2,  test-tube  cultures  with  acidulated  agar. 

Nos.  36-40,  Aug.  2,  infection  experiments  with  dead  chinch-bugs. 

No.  41,  Aug.  2,  infection  experiment  with  dead  cabbage  worms. 
No.  42,  July  3,  fruit-jar  culture  on  corn-meal  batter. 
No.  43,  July  3,  test-tube  agar  culture. 

Nos.  44  and  45,  July  20,  fruit-jar  cultures  on  acidulated  corn-meal 
batter. 

Nos.  46  and  47,  July  20,  infection  experiments  with  dead  chinch- 
bugs. 

No.  48,  July  27,  agar  culture,  temperature  test. 

No.  49,  July  30,  agar  culture,  temperature  test. 

No.  50,  July  27,  agar  culture,  temperature  test. 

No.  51,  July  27,  infection  experiment  with  cabbage  worms. 

No.  52.  Aug.  2,  infection  experiment  with  sphinx  larva. 
No.  fj,  April  20,  field  experiment,  Hollenbeck  farm. 
No.  54,  May  25,  laboratory  contagion  box,  Kansas  chinch-bugs. 
No.  55,  June  7,  field  experiment,  Wells  farm. 
No.  56,  June  7,  contagion  box  and  field  experiment,  Wells  farm. 

No.  57,  June  10,  field  experiment,  Wells  farm. 

No.  58,  June  10,  field  experiment,  Wells  farm. 
No.  59,  June  7,  contagion  box,  field  experiment,  Smith  farm. 

No.  60,  June  15,  field  experiment,  Smith  farm. 
No.  61,  June  15,  field  experiment,  University  farm. 
No.  62,  June  18,  field  experiment,  University  farm. 
No.  63,  June  19,  field  experiment,  Hartley  farm. 
No.  68,  June  22,  large  contagion  box  in  laboratory. 

No.  64,  Aug.  6,  field  experiment,   Bartley  farm.      (See  also  under 
No.  2.) 

No.  65,  Aug.  6,  field  experiment,  Bartley  farm.     (See  also  under 
No.  2.) 

No.  66,  Sept.  4,  field  experiment,  Bartley  farm. 

No.  73,  Aug.  7,  field  experiment,  Ferguson  farm. 
No.  69,  June  23,}large  contagion  box  in  laboratory. 

No.  70,  June  27,  large  contagion  box  in  laboratory. 
No.  77,  May  15  and  June  10,  field  experiment,  Heth  farm. 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  4! 

No.  78,  June  25,  field  experiment,  Wilson  farm. 
No.  79,  July  i,  field  experiment,  Jackson  farm. 
No.  80,  June  20,  field  experiment,  Filson  farm. 
No.  76,  Oct.  6,  spontaneous  outbreak,  Hurd  farm. 

DESCRIPTION    OF    EXPERIMENTS, 
i.     EXPERIMENTS  WITH  THE  FUNGI  OF  CONTAGIOUS  DISEASE. 

The  season's  operations  with  contagious-disease  experiments  were 
developed  principally  from  two  points  of  departure:  the  first  a  single 
insect  larva,  indeterminable  as  to  species,  found  April  17  dead  and 
covered  with  the  fungus  of  white  muscardine,  in  a  plowed  corn  field 
near  Urbana;  and  the  second  a  small  lot  of  chinch-bugs  dead  with  the 
same  fungus  infection,  received  from  Chancellor  Snow  of  the  Univer- 
sity of  Kansas  about  May  15.  From  the  first-mentioned  material 
numerous  cultures  were  made,  and  infection  experiments  were  con- 
ducted on  chinch-bugs,  cabbage  worms,  and  other  insect  larvae,  the 
series  of  operations  dependent  upon  this  original  specimen  extending 
from  April  21  to  September  20.  From  the  second  lot  various  laboratory 
and  field  experiments  were  started — twenty-one  in  number — extending 
from  May  25  to  October  10,  all  having  the  character  of  direct  or  indi- 
rect exposures  of  living  chinch-bugs  to  contagion  or  infection  by  means 
of  these  dead  specimens  obtained  from  Dr.  Snow. 

Although  several  of  the  experiments  here  described  were  incom- 
plete or  otherwise  unsatisfactory,  I  have  thought  it  best  to  report  the 
whole  mass  of  them,  as  an  assurance  (if  for  no  other  reason)  that 
nothing  has  been  withheld  because  of  its  unsatisfactory  character. 

No.  i.  April  21.  A  test-tube  culture  on  agar,  from  a  dead  insect  larva  of  unde- 
termined species,  found  in  a  field  at  Urbana,  Illinois.  April  24,  had  barely  begun  to 
grow.  April  27  spores  had  formed.  April  30,  spores  ripe,  the  culture  unmistakably 
Sporotrichum  globuliferum.  This  larva  and  the  culture  derived  from  it  are  the  start- 
ing point  for  all  experiments  of  this  list  to  No.  52  inclusive,  as  well  as  for  Nos.  64, 
65,  67,  71,  74,  and  75  additional. 

No.  2.  May  7,  six  Mason  fruit  jars,  with  caps  altered  to  facilitate  sterile  culture 
(see  Plate  V,  Fig.  i),  partly  filled  with  a  batter  of  corn  meal  and  beef  broth  and 
sterilized  by  dry  heat  for  one  hour  on  each  of  two  successive  days,  were  inoculated 
by  spores  of  the  muscardine  fungus  taken  from  culture  No.  i.  This  second  culture 
was  successful,  and  furnished  material  for  a  large  amount  of  subsequent  experimen- 
tal work. 

No.  3.  May  n,  a  lot  of  chinch-bugs  received  from  F.  O.  Pierce,  of  Xenia,  Clay 
.county,  was  treated  with  spores  from  culture  No.  i  and  placed  in  a  small  wooden  box 
which  was  kept  on  wet  earth  under  a  hedge,  and  covered  again  with  a  box  of  larger 
size.  May  16  these  bugs  began  to  die.  By  the  22d  all  were  dead  but  one,  and  an 
external  growth  of  the  Sporotrichum  had  begun  to  appear  upon  three.  All  were 
then  returned  to  the  sender  for  distribution  in  his  fields. 

No.  4.  A  precisely  similar  experiment  with  chinch-bugs  from  Trenton,  Illinois, 
was  begun  May  16,  the  experimental  box  being  similarly  placed.  On  the  igth  some 
of  the  bugs  were  dead;  on  the  22d  an  external  fungous  growth  appeared  upon  two  of 


42  BULLETIN   NO.   38.  \_March, 

them,  as  yet,  however,  without  spores;  on  the  25th  many  more  were  dead,  several  of 
them  covered  with  a  white  mycelium;  and  by  the  2gth  nearly  all  had  perished,  devel- 
opment of  the  characteristic  spores  on  several  of  them  now  giving  unmistakable  evi- 
dence of  the  presence  of  S.  globuliferum — the  special  fungus  of  the  muscardine 
disease.  Specimens  returned  to  the  sender. 

No.  5.  On  the  iyth  of  May  a  second  lot  of  bugs  from  Xenia  was  similarly 
treated,  with  a  similar  result.  Beginning  to  die  May  19,  most  of  the  bugs  were  dead 
on  the  22d,  and  on  the  2Qth  all  had  perished.  A  slight  external  growth  appearing  at 
this  date  resembled  in  every  way  the  immature  mycelium  of  the  muscardine  fungus. 
Without  waiting  for  further  evidence  of  infection  this  lot  of  bugs  was  returned  to  the 
sender. 

No.  6.  Next,  on  the  28th  of  June,  nearly  two  months  from  the  original  agar 
culture  (No.  i),  a  second  agar  tube  was  infected  from  that  growth.  July  6,  this 
culture  was  ripe,  and  the  spores  were  used  for  the  experiment  next  succeeding. 

No.  7.  July  6  a  test-tube  mixture  of  corn  meal  and  agar  gelatine  was  infected 
from  culture  No.  6 — the  third  remove  from  the  dead  insect.  July  9  this  had  made 
a  good  start,  but  was  not  followed  further. 

No.  8.  July  6.  This  was  an  experiment  identical  with  No.  7,  and  begun  at  the 
same  time,  varying  only  in  the  culture  medium  used,  which  was  a  batter  of  corn  meal 
mixed  with  water  in  which  potatoes  had  been  boiled.  Three  days  later,  July  9,  the 
spores  were  starting  abundantly,  but  the  matter  was  not  followed  further. 

No.  9.  July  6.  This  was  a  companion  experiment  to  the  two  preceding,  except 
that  our  ordinary  mixture  of  corn  meal  and  beef  broth  was  used  in  place  of  the  fore- 
going media.  July  9,  growth  had  begun,  but  less  vigorously  than  on  either  of  the 
others. 

No.  10.  July  9.  A  corn-meal  batter,  like  that  of  No.  9,  but  acidulated  with  acetic 
acid,  was  infected  with  ripe  spores  from  No.  i.  July  n  it  had  made  a  good  start, 
but  was  not  followed  further. 

Nos.  7  to  10,  derived  from  No.  6,  were  intended  originally  to  test 
the  comparative  value  of  various  corn-meal  mixtures.  The  exigencies 
of  the  season's  work  prevented  their  completion,  and  they  serve  merely 
to  give  some  hints  suggestive  of  further  trials. 

No.  ii.  July  2.  This  was  a  repetition  of  No.  6 — a  set  of  agar  test-tube  cultures, 
twelve  in  all,  the  spores  for  which  were  derived  from  No.  i.  July  5  all  were  freely 
growing,  and  July  9  the  growth  was  spreading  rapidly.  These  tubes  were  not  again 
reported  on  until  August  13,  at  which  time  an  abundant  development  of  spores  of  the 
muscardine  fungus  was  noted  on  all,  the  gelatine  having,  however,  in  the  meantime 
quite  dried  up.  A  long  series  of  cultures  on  corn  meal  and  of  infection  experiments 
on  chinch-bugs  and  cabbage  worms,  and  other  larvae,  were  made  with  spores  from  this 
set  of  tubes. 

No.  12.  July  13,  1:30  p.  m.,  several  fruit  jars  of  the  corn-meal  mixture  with 
beef  broth,  neutralized  with  sodium  carbonate,  were  infected  with  spores  from 
No.  ii.  Two  days  later,  July  15,  these  spores  had  begun  to  grow,  and  on  the  i7th 
the  growth  covered  a  part  of  the  surface. 

No.  13.  July  13,  at  1:30  P.  M.,  spores  from  No.  ii  were  sown  on  acidulated  mix- 
ture of  corn-meal  and  beef  broth  which  had  been  placed  in  altered  Mason  fruit  jars 
and  sterilized  by  heat  as  already  described.  On  the  isth  growth  had  begun,  and  on 
the  i7th  the  surface  of  the  meal  was  covered. 

No.  14.  July  17,  at  2  o'clock  p.  M.,  fourteen  Mason  fruit  jars  with  the  acid  mix- 
ture of  corn  meal  and  beef  broth,  sterilized  by  heat  on  two  successive  days,  were 
infected  with  spores  from  No.  n.  On  the  igth  the  growth  had  started,  and  on  the 
2ist  it  had  become  very  abundant,  distinctly  more  so  indeed  on  both  these  acid  mix- 
tures (13  and  14)  than  on  the  neutral  mixture  No.  12. 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  43 

No.  15.  July  31.  An  infection  experiment  on  living  cabbage  worms  with  spores 
from  the  acid  corn-meal  culture,  No.  14  of  this  list.  Two  cabbage  worms  were 
infected  on  the  back  near  the  head,  and  were  then  shut  up  in  a  large  covered  glass  dish 
which  had  a  layer  of  moist  sand  on  the  bottom,  on  which  a  fresh  cabbage  leaf  was 
placed  for  food.  August  i,  no  growth  has  appeared  on  either  cabbage  worm.  August 
2,  still  no  growth,  but  one  of  the  larvae  has  pupated.  August  3,  still  no  growth. 
August  7,  one  larva  dead,  softened,  and  blackened,  but  without  appearance  of  fungus 
contamination.  The  pupa  also  dead  and  softening.  August  13,  no  Sporotrichum 
apparent,  only  softened  bodies  of  larva  and  pupa  remaining. 

No.  16.  July  31.  An  experiment  parallel  with  the  preceding,  three  cabbage 
worms  being  infected  on  the  back.  Results  identical  with  those  of  No.  15,  one  worm 
pupating  August  2.  Both  larvae  and  pupa  died,  blackening  and  becoming  deliques- 
cent, without  appearance  of  muscardine.  The  pupating  larva  proved  to  have  been 
parasitized,  as  is  noted  August  7. 

These  two  experiments  with  infection  material  derived  from  acid 
cultures  throw  some  doubt  on  the  effectiveness  of  that  kind  of  material, 
but  as  the  larvae  evidently  died  from  the  common  bacterial  disease  of  the 
cabbage  worm,  it  is  possible  that  the  previous  presence  of  this  disease 
prevented  the  development  of  the  fungus,  an  hypothesis  that  is  made 
more  probable  by  the  fact  that  spores  of  Sporotrichum  will  not  germi- 
nate on  decaying  media. 

No.  17.  July  28.  An  infection  experiment  upon  the  larva  of  a  butterfly  (Grapta 
interrogationis)  taken  from  the  elm.  This  caterpillar  was  infected  with  spores  from 
agar  culture  No.  n,  itself  derived,  as  will  be  remembered,  from  agar  culture  No.  i, 
derived  in  turn  from  the  dead  larva  with  which  this  series  began.  The  material  here 
used  was  consequently  at  two  removes  from  the  dead  insect.  The  spores  were  placed 
along  the  center  of  the  back  of  the  caterpillar  at  10:30  A.  M.,  the  infected  insect  being 
then  shut  up  in  a  large  covered  glass  dish,  with  a  layer  of  moist  sand  on  the  bottom, 
upon  which  leaves  of  elm  were  scattered  as  food.  At  9  A.  M.,  July  30,  this  larva  had 
pupated,  of  course  casting  off  the  skin  upon  which  the  spores  had  been  placed.  It 
was  examined  daily  without  note  of  change  until  August  7.  The  pupa  at  this  date 
was  still  alive  and  apparently  healthy,  but  exhibited  a  slight  growth  of  Sporotrichum 
from  a  point  about  the  size  of  a  pin  head  on  the  ventral  surface,  at  the  edge  of  the 
pupal  wing-pads.  This  ventral  point  was  in  immediate  contact  with  the  cast  skin  still 
bearing  the  fungus  spores.  August  13  this  pupa  was  dead,  with  a  slight  external 
growth  of  Sporotrichum  globulifcrum — at  that  time  in  fruit. 

No.  18.  July  28,  10:00  A.  M.  An  infection  experiment  similar  to  the  preceding, 
except  that  a  cabbage  worm  (Pteris  rapae)  was  used  instead  of  the  Grapta  larva,  and  that 
a  cabbage  leaf  was  placed  in  the  dish  instead  of  leaves  of  the  elm.  The  caterpillar  was 
touched  with  spores  from  No.  n  on  the  back,  immediately  behind  the  head.  July  30 
the  fungus  was  growing  freely  from  the  point  of  infection  and  spreading  to  the  sides 
of  the  body.  July  31  it  had  enveloped  the  body  near  the  head,  and  had  also  extended 
on  the  ventral  surface  the  entire  length  of  the  caterpillar.  The  color  of  the  larva 
had  in  the  meantime  changed  to  that  of  crushed  raspberries  wherever  the  fungus 
was  growing,  and  August  i  the  entire  cabbage  worm  was  of  the  same  crushed-rasp- 
berry color.  August  2  the  Sporotrichum  had  spread  all  over  the  surface,  and  August 
7  it  was  well  developed  everywhere  and  covered  with  ripe  spores. 

No.  19.  July  28.  An  infection  experiment  precisely  like  the  last,  except  that 
the  spores  were  placed  along  the  right  side  of  the  caterpillar  only.  Two  days  later 
the  fungus  growth  was  abundant  all  along  this  side  wherever  the  spores  had  lodged, 
but  it  had  not  yet  begun  to  spread.  A  very  fine  white  web  had  fastened  the  larva  to 
the  o,ish  upon  which  it  was  resting  when  it  died.  July  31  nearly  the  entire  body  was 


44  '  BULLETIN  NO.  38.  \_March, 

covered  by  the  mycelium  of  Sporotrichum,  leaving  only  the  two  ends  free,  and  the 
larva  had  begun  to  change  to  the  crushed-raspberry  color.  August  2  the  whole 
body  was  covered,  and  later  the  spores  developed  everywhere,  as  before. 

No.  20.  July  28.  Like  the  preceding,  except  that  the  spores  were  applied  only 
at  the  posterior  end  of  the  back.  July  30,  growth  abundant  at  the  point  of  infection, 
covering  about  a  fourth  of  the  back,  but  not  extending  downwards  to  the  sides.  A 
very  fine  white  web  fastens  the  larva  to  the  cover  July  31,  growth  of  mycelium  very 
abundant  at  point  of  infection,  and  extending  downwards,  underneath  the  body,  to 
the  hinder  end,  the  crushed-raspberry  color  appearing  wherever  the  fungus  has  taken 
hold.  August  i,  growth  slowly  extending  downwards.  August  7,  spores  well  devel- 
oped on  the  dead  larva. 

Experiments  15,  16,  18, 19,  and  20  of  the  foregoing  series  show  the 
efficiency  of  this  fungus  as  a  means  of  infecting  living  cabbage  worms, 
and  bring  to  light  also  the  interesting  fact  that  its  growth  may  have  the 
effect  to  color  the  larva  red. 

We  have  next  a  series  of  experiments  intended  to  test  the  possi- 
bility of  the  growth  of  Sporotrichum  on  insects  dead  when  infected. 
For  this  purpose,  cabbage  worms  killed  with  chloroform  were  used. 

No.  21.  July  30,  1:30  P.  M.  Chloroformed  cabbage  worm  placed  on  piece  of 
cabbage  leaf  on  moist  sand,  spores  of  muscardine  (Sporotrichum)  from  No.  n,  sown 
along  the  back.  July  31,  8:30  A.  M.,  no  growth  visible.  August  i,  9  A.  M.,  slight 
growth  along  the  back.  August  2,  8:30  A.  M.,  growth  very  abundant  on  the  back. 
August  7,  3  P.  M.,  Sporotrichum  well  developed  on  this  larva.  Specimen  preserved. 

No.  22.  July  30.  This  was  an  experiment  like  No.  21,  except  that  the  cabbage 
worm  was  infected  on  the  ventral  surface.  July  31,  growth  not  started.  August  i, 
beginning  to  grow.  August  2,  growth  very  abundant  and  spreading  over  the  entire 
body.  August  7,  Sporotrichum  well  developed.  Specimen  preserved. 

No.  23.  July  30.  Same  as  the  foregoing,  but  infected  along  the  side.  Examined 
August  i,  2,  3,  and  7,  with  results  exactly  as  above. 

No.  24.  July  30.  Exactly  as  above,  except  that  several  caterpillars  were  infected 
on  the  head.  July  31,  growth  not  started.  August  i,  no  growth  as  yet,  except  that 
a  fine  cobweb  fungus  has  started  on  a  single  worm.  August  2,  the  above  worm  com- 
pletely enveloped  in  the  cobweb  growth.  August  3,  germination  of  spores  just  begin- 
ning to  show.  At  this  point  the  above  experiment  was  accidentally  interrupted. 

Nos.  25,  26,  and  27.  July  31.  Dead  cabbage  worms  as  above.  Experiments 
identical  with  the  foregoing,  and  made  at  the  same  date,  except  that  infected  spots 
were  touched  with  sterilized  distilled  water  to  cause  the  spores  to  adhere  to  the  worm. 
The  results  were  all  as  above  mentioned,  with  a  slight  variation  in  No.  27.  Here, 
August  i,  no  growth  of  the  spores  had  appeared,  but  one  larva  had  become  fastened 
to  the  cover  by  a  fine  white  web.  On  the  2d  the  growth  was  spreading  feebly,  and  on 
the  3d  the  worms  were  turning  crushed-raspberry  color,  the  one  on  the  cover  having 
the  Sporotrichum  growth  well  started.  August  7  this  fungus  was  fully  developed  on 
all,  and  the  specimens  were  put  aside  for  preservation. 

No.  28.  July  31,  10  A.  M.  Three  pupae  of  cabbage  worms  placed  under  same 
conditions  as  No.  21,  and  infected  with  Sporotrichum  from  No.  n.  August  i,  no 
growth.  August  2,  two  of  the  pupae  turning  reddish,  but  no  growth.  August  3,  still 
no  growth,  but  one  of  the  pupae  of  a  deep  red  tint.  August  7,  two  of  the  pupae  dead, 
one  of  them  showing  a  slight  mycelial  growth  of  Sporotrichum.  The  third  has 
yielded  a  healthy  butterfly. 

Nos.  29  to  35  are  agar  test-tube  cultures,  in  which  the  gelatine  was 
acidulated  variously,  it  being  the  purpose  of  these  experiments  to  deter- 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  45 

mine  the  degree  of  acidity  of  the  medium  most  favorable  to  the  germi- 
nation of  the  spores  and  the  development  of  the  fungus. 

No.  29.  August  2,  3^  cc.  of  agar  gelatine  and  i  cc.  of  a  one-eighth  per  cent,  solu- 
tion of  acetic  acid  in  test  tube,  sown  with  spores  of  Sporotrichum  globuliferum  from 
No.  ii.  August  13,  no  Sporotrichum  growing,  spores  apparently  not  having  started. 

No.  30.  August  2.  Like  29,  except  that  the  acetic  acid  was  in  a  one-fourth  per 
cent,  solution.  August  13,  there  has  been  apparently  a  slight  growth  of  Sporotrichum 
in  this  tube,  but  it  is  now  all  dead. 

No.  31.  August  2.  Like  29,  except  that  the  acetic  acid  used  was  a  one-half  per 
cent,  solution.  August  13,  a  small  straggling  growth  of  Sporotrichum  has  appeared 
and  has  formed  spores. 

No.  32.  August  2.  As  above,  except  that  the  acetic  acid  was  a  one  per  cent, 
solution.  August  13,  fair  growth  of  Sporotrichum,  covering  most  of  the  agar  surface. 
Spores  abundant,  ripe,  but  not  of  yellowish  tint. 

No.  33.  August  2.  As  above,  acetic  acid  now  a  two  per  cent,  solution.  Result 
identical  with  No.  32. 

No.  34.  August  2.  Like  No.  29,  except  that  the  solution  of  acetic  acid  is  now 
five  per  cent.  August  13,  no  growth  whatever. 

No.  35.  Like  No.  29,  except  that  the  acetic  acid  used  was  a  ten  per  cent,  solution. 
August  13,  no  growth. 

From  the  foregoing  it  appears  that  an  agar  mixture  containing 
from  three  to  six  hundreths  of  one  per  cent,  of  acetic  acid  is  that  which 
proved  most  favorable  to  the  growth  of  Sporotrichum. 

Next,  I  report  six  experiments  with  dead  chinch-bugs,  intended  to 
test  the  possibility  of  the  infection  of  this  insect,  after  death  by  other 
causes. 

No.  36.  August  2.  Fifteen  chinch-bugs  killed  by  crushing  were  placed  in  a 
covered  glass  dish,  and  treated  with  spores  from  culture  No.  n.  August  3,  no 
appearance  of  growth.  August  7,  the  dish  a  mass  of  mould,  which  fills  the  entire 
interior;  no  appearance  of  a  growth  of  Sporotrichum  on  the  bugs.  August  13,  no 
development  of  Sporotrichum  in  this  experiment. 

No.  37.     August  2.     A  duplicate  of  No.  36,  with  precisely  the  same  result. 

No.  38.  August  2.  Chinch-bugs  killed  with  chloroform,  placed  on  a  cabbage  leaf 
on  moist  sand  in  a  covered  glass  dish  and  infected  with  Sporotrichum  from  No.  n. 
August  3,  no  growth.  August  7,  no  appearance  of  infection;  specimens  beginning  to 
mould.  August  13,  no  Sporotrichum  to  be  found. 

No.  39.  August  2.  Equivalent  experiment,  except  that  the  bugs  were  placed 
immediately  on  sand.  No  growth,  August  3.  August  7,  3  P.  M.,  slight  appearance  of 
Sporotrichum  on  legs,  antennae,  etc.,  of  single  insects,  here  and  there. 

No.  40.  August  2.  The  same  as  38.  August  3,  no  growth.  August  7,  loosely 
covered  with  bluish  mould;  no  Sporotrichum  formed. 

No.  41.  August  2.  Infection  experiment  with  dead  cabbage  worms.  Equiva- 
lent of  No.  25.  August  3,  no  growth.  August  4,  development  of  Sporotrichum  com- 
mencing on  all  these  cabbage  worms.  August  7,  Sporotrichum  well  grown,  with 
some  appearance  of  post  mortem  mould. 

No.  42.  July  3.  A  fruit-jar  culture  on  corn-meal  batter  made  with  beef  broth, 
the  spores  for  which  were  taken  directly  from  agar  culture  No.  i.  A  successful 
growth,  not  requiring  detailed  report. 

No.  43.  July  3.  An  agar  culture  in  five  test-tubes,  made,  like  42,  from  No.  i. 
Developed  readily  and  matured  in  due  season,  being  subsequently  used  for  a  con- 
siderable number  of  cultures  and  infections. 

No.  44.  July  20.  Fifteen  jars  of  the  acidulated  corn-meal  mixture  (degree  of 
acidity  not  given)  infected  with  Sporotrichum  from  No.  43  at  1:30  P.  M.  These 


46  BULLETIN   NO.   3$.  [March, 

cultures  were  all  well  started  July  23,  and  matured  in  due  season,  eight  of  the  fifteen 
being,  however,  somewhat  contaminated  by  Aspergillus.  The  contents  of  these  jars 
were  subsequently  used  in  part  for  chinch-bug  infection  experiments  on  the  large  scale. 

No.  45.  July  20.  Culture  like  44,  differing  only  by  an  abbreviation  of  the  ster- 
ilization process.  Previous  to  this  the  jars  had  first  been  sterilized  by  heat  while 
empty,  then  stocked  with  the  corn-meal  mixture  and  sterilized  again.  In  the  present 
culture,  jars  and  batter  were  sterilized  together,  once  for  all.  Result  the  same  as  44. 

No.  46.  July  20.  Chinch-bugs  killed  by  chloroform  were  placed  dry  in  a  test- 
tube,  treated  with  Sporotrichum  from  43,  and  left  with  the  test-tube  plugged  with  cot- 
ton. July  28,  no  fungus  growth.  • 

No.  47.  July  20.  Like  46,  except  that  the  chinch-bugs  were  moistened  with 
distilled  water  before  being  placed  in  the  tube.  July  28  and  August  13,  no  growth  at 
either  date. 

July  27,  a  beginning  was  made  with  experiments  intended  to  deter- 
mine the  temperature  at  which  Sporotrichum  would  grow  most  freely. 

No.  48.  July  27,  ii  A.  M.  An  agar  test-tube  sown  with  spores  from  No.  43  and 
kept  in  laboratory  at  temperature  of  80°  Fah.  July  28,  8.30  A.  M.,  74°  Fah.;  11:30, 
79°  Fah.  July  30,  8:15  A.  M.,  74°  Fah.,  growth  starting  nicely.  The  average 
temperature  by  day  in  this  culture  was  about  77°. 

No.  49.  July  30.  Another  tube,  as  above,  placed  in  south  window,  temperature 
ranging  from  77°  to  95°  Fah.  July  30,  growth  started  well. 

No.  50.  July  27.  Agar  tube,  as  above,  placed  in  incubator  at  97°  Fah.  at  n  A. 
M.,  and  kept  there  at  a  constant  temperature  of  100°  Fah.  July  30,  growth  not 
starting.  August  13,  these  spores  did  not  germinate. 

No  51.  July  27.  An  experiment  with  cabbage  worms  infected  from  No.  43. 
Several  caterpillars  (Pieris  rapae]  placed  under  a  sterilized  glass  bell-jar  with  a  large 
piece  of  fresh  cabbage  leaf  lying  on  table  without  moist  sand.  Spores  were  shaken 
from  agar  culture  and  spread  upon  the  worms  with  a  sterilized  platinum  wire.  July 
30,  several  worms  have  died,  but  without  appearance  of  fungous  growth.  One  example, 
however,  shows  growth  near  the  hinder  end,  and  has  turned  black  about  one-fourth 
of  its  length.  July  31,  the  cabbage  worm  just  mentioned  has  turned  a  crushed- 
raspberry  color,  and  the  Sporotrichum  has  begun  to  spread  over  the  surface.  Another 
larva  has  turned  a  similar  color,  and  a  Sporotrichum  growth  is  appearing  at  one 
point.  August  i,  several  of  the  worms  have  become  crushed-strawberry  color,  but 
without  visible  growth.  One  has  become  brownish-green,  and  on  this  Sporotrichum 
filaments  have  appeared  externally.  August  7,  everything  dead  but  one  imago 
recently  emerged.  Ten  died  in  pupa  stage;  two  larvae  parasitized.  August  13,  very 
little  external  development  of  fungus  has  appeared  in  this  lot  of  worms. 

No.  52.  August  2.  Large  sphinx  larva  (Protoparce)  chloroformed,  and  placed  in 
a  large  culture  dish  upon  a  cabbage  leaf  resting  on  moist  sand.  Spores  from  culture 
43  sown  upon  the  right  side.  August  3,  no  growth.  August  7,  mixture  of  fungi  all 
over  surface,  but  infected  area  with  a  conspicuous  white  patch.  August  13,  no 
Sporotrichum  globuliferum,  only  common  mould. 

No.  53.  This  is  a  farmer's  contagion  experiment  made  by  Mr.  C.  S.  Hollenbeck, 
near  Tonti,  Illinois,  and  not  observed  by  us  in  the  beginning.  Infection  material 
originally  obtained  from  my  office  September  7,  1893,  and  used  to  start  contagion 
box,  the  contents  of  which  were  afterwards  distributed  in  his  fields  with  a  result 
which  he  regarded  as  successful  last  fall.  The  box,  with  a  considerable  number  of 
chinch-bugs  remaining,  was  kept  over  winter  in  a  warm  and  rather  moist  cellar,  and 
about  April  20  its  contents  were  scattered  in  wheat  in  a  young  orchard,  care  being 
taken  to  place  the  material  where  bugs  were  thickly  congregated.  The  weather  at 
the  time  was  damp,  cloudy,  and  warm.  Mr.  Hollenbeck  reports  that  about  a  week 
afterwards  he  saw  many  mouldy  bugs  in  the  field,  other  than  those  put  out,  and  was 
convinced  that  these  bugs  were  killed  by  fungus  disease. 


1895.]  EXPERIMENTS    WITH    CHINCH-BUGS.  47 

May  24  this  wheat  was  examined  by  Mr.  Marten,  who  reported  the  chinch-bugs 
very  abundant  in  the  wheat,  copulating  and  depositing  eggs  Search  for  the  greater 
part  of  a  day  on  this  farm  and  one  adjacent,  yielded  only  two  fungus-covered  chinch- 
bugs.  On  another  visit,  made  June  5,  the  fungus  disease  was  found  generally 
distributed  in  this  and  adjoining  fields,  as  it  was  at  that  time  throughout  this  part  of 
the  state  at  large;  but  June  20,  after  an  interval  of  drought,  no  trace  of  it  could  be 
found  by  Mr.  Marten  in  these  same  fields.  The  young  bugs  at  this  time  were 
plentiful,  a  few  having  reached  the  pupa  stage. 

No.  54.  A  contagion  experiment,  the  first  of  a  long  series  (see  Outline,  page 
40)  derived  from  a  small  lot  of  chinch-bugs,  dead  with  Sporotrichum  globuliferum, 
received  from  Dr.  Snow  about  May  15.  May  25  a  lot  of  chinch  bugs  from  the  vicinity 
of  Tonti  and  Odin,  in  Marion  county,  collected  by  Mr.  Marten,  together  with  others 
received  from  fourteen  farmers  of  that  vicinity,  were  placed  in  a  wooden  box  which 
had  been  thoroughly  wet  inside  and  out,  and  the  bottom  of  which  was  covered  with  a 
layer  of  green  wheat  for  food.  With  these  bugs  the  material  obtained  from  Dr.  Snow 
was  placed.  The  box  so  prepared  was  tightly  closed  and  kept  on  damp  sand  upon  the 
ground  in  the  insectary.  It  was  opened  for  examination  about  every  other  day  and  sup- 
plied with  fresh  food.  May  26  more  bugs  were  added,  but  no  dead  insects  were 
observed.  May  28  another  lot  from  southern  Illinois  was  introduced,  and  still  another 
on  the  2gth.  No  dead  were  seen  at  this  time,  and  there  were  no  traces  of  muscardine 
infection.  On  the  3oth  a  few  bugs  were  dead  in  the  box,  two  of  them  well  covered 
with  another  chinch-bug  fungus,  Entomophthora  aphidis,  but  no  fresh  Sporotrichum 
was  seen. 

More  live  insects  were  introduced  May  31  and  June  i,  at  which  latter  date  the 
dead  bugs  were  a  little  more  numerous.  June  4,  the  box  had  warped  and  split,  and 
more  than  half  the  bugs  escaped;  otherwise  the  experiment  was  in  good  condition. 
The  white  muscardine  had  now  taken  effect,  and  a  sufficient  number  of  fungus- 
covered  chinch-bugs  were  taken  out  to  supply  the  fourteen  farmers  near  Tonti  and 
Odin  from  whom  the  material  was  received  May  25,  together  with  four  other  farmers 
at  Farina,  in  Fayette  county.  Among  these  last  were  G.  C  Wells  and  James  Smith, 
whose  farms  were  frequently  visited  by  us  later.  The  lot  sent  to  Tonti  and  Odin  was 
delivered  June  5,  and  that  to  Mr.  Wells  and  Mr.  Smith  June  7,  a  part  of  this  latter 
material  being  used  by  Mr.  Marten  for  the  field  experiment  on  the  Wells  farm, 
reported  at  length  under  No.  55. 

June  9  all  the  material  was  taken  from  the  above  box  and  placed  in  a  second 
similar  one.  June  n  this  second  box  was  overhauled  and  a  sufficient  number  of 
fungus-covered  bugs  was  removed  to  make  up  twenty  packages,  two  lots  of  living  bugs 
being  at  the  same  time  added.  June  12  and  13  more  live  bugs  were  added,  and  a  few 
dead  ones  were  taken  out.  June  14  the  condition  of  this  lot  was  regarded  as 
unsatisfactory,  and  everything  was  again  transferred  to  a  clean  box.  Of  those  which 
were  dead  a  few  were  covered  with  muscardine  fungus,  but  at  least  a  hundred  times 
as  many  gave  no  external  trace  of  muscardine.  Five  additional  lots  from  various 
places  were  now  introduced,  and  the  box  was  a  second  time  infected,  by  means  of 
fifty  chinch-bugs  covered  with  ripened  Sporotrichum  collected  by  Mr.  Marten  in 
wheat  fields  at  Tonti  and  Farina  June  6  and  7  (see  No.  55).  June  15  thirteen  lots 
more  were  placed  in  this  box,  and  a  quantity  of  fungus-covered  dead  were  removed 
and  distributed  in  spring  wheat  on  the  University  experimental  farm  (see  No.  61). 
June  16  a  quantity  was  taken  out  for  shipment,  and  seventeen  packages  from  farmers 
were  introduced.  June  17  six  lots  more  were  placed  in  this  box,  and  June  18  four 
more  On  this  last  date  both  old  and  young  were  dying  with  white  muscardine,  and 
a  few  with  Entomophthora.  About  three  thousand  live  bugs  from  this  box  were  now 
distributed  in  spring  wheat  on  the  University  farm  (see  No.  62),  and  a  lot  of  dead 
bugs  removed  and  prepared  for  shipment,  together  with  a  quantity  of  both  dead  and 
living  for  use  in  fields  in  southern  Illinois  (see  No.  63).  June  20,  box  overhauled,  dead 


48  BULLETIN    NO-    38.  [March, 

bugs  removed  and  distributed  to  farmers.  June  22,  enough  material  removed  to 
supply  fifty-one  farmers,  after  which  the  entire  contents  were  transferred  to  two  large 
boxes  in  Natural  History  Hall  (see  Nos.  68  and  69). 

No.  55.  June  7.  A  field  infection  experiment,  started  by  Mr.  Marten  in  a  4^- 
acre  wheat  field  on  the  Wells  farm,  represented  at  A,  Plate  I.  Chinch-bugs 
abundant,  literally  covering  the  wheat  in  many  places,  especially  in  the  northeast 
corner  adjoining  corn  (D).  A  dozen  bugs  dead  with  the  white  fungus,  collected  from 
the  ground  in  wheat  at  this  time,  were  afterwards  placed  in  No.  54.  Diseased  insects 
locally  present  in  all  fields  examined.  About  one  hundred  fungus-covered  chinch- 
bugs  from  No.  54  distributed  along  the  second  and  third  drill  rows,  at  the  bases  of 
plants  where  live  bugs  were  most  numerous,  for  a  distance  of  several  rods  on  the 
north  and  east  sides,  in  the.  northeast  corner  (indicated  by  the  heavy  dotted  lines 
on  Plate  I). 

June  19,  field  examined  by  Mr.  Marten.  Fungus-covered  bugs  about  as  abundant 
throughout  the  wheat  as  on  the  former  visit.  No  indication  that  the  disease  had 
spread,  or  was  any  more  prevalent  in  the  vicinity  of  the  spot  where  the  dead  bugs 
were  distributed  than  at  other  places.  Many  fields  examined  in  this  neighborhood 
not  entered  on  former  visit.  Diseased  bugs  found  in  all  in  moderate  numbers.  A 
second  lot  of  infection  material,  consisting  of  several  hundred  bugs  dead  with  this 
fungus,  from  No.  54,  scattered  on  the  ground  in  several  drill  rows  in  the  immediate 
vicinity  of  those  previously  distributed.  Wheat  badly  damaged  and  considerably 
lodged  in  several  places.  Bugs  everywhere  abundant,  advancing  into  corn  (B  and  D). 
June  20  Mr.  Marten  revisited  the  field  (A)  to  examine  two  spots  (a  and  l>),  each  about 
one  rod  in  diameter,  where  manure  had  been  piled  previous  to  being  scattered,  and 
where  the  wheat  was  badly  lodged.  The  ground  was  here  quite  damp,  and  chinch- 
bugs  had  collected  in  considerable  numbers.  The  muscardine  fungus  was  also  much 
more  abundant  here  than  elsewhere  in  the  field,  and  several  hundred  whitened  bodies 
could  have  been  collected.  It  was,  however,  thought  advisable  to  allow  them  to 
remain,  in  order  to  determine,  if  possible,  whether  or  not  the  disease  would  spread 
from  these  centers  of  spontaneous  development.  Wheat  cut  June  25,  but  so  far  as 
could  be  seen,  according  to  Mr.  Wells,  the  fungus  had  not  spread. 

July  ii  a  few  traces  of  the  original  material  were  found  by  Mr.  Marten  in  the 
northeast  corner.'  A -few  whitened  bodies  were  under  the  fallen  wheat  at  a  and  b,  but 
the  fungus  was  apparently  a  week  or  ten  days  old,  and  there  was  no  indication  that  the 
disease  had  spread  from  these  places.  Only  an  occasional  live  insect  seen  in  the  stub- 
ble, the  great  majority  having  migrated  into  adjoining  corn,  B  and  D,  where  consider- 
able mischief  was  done.  Several  rows  in  the  latter  field  had  already  been  killed,  and  the 
corn  was  blackened  with  bugs  for  several  rods.  In  the  former  field,  however,  these 
bugs  were  not  quite  so  abundant,  their  progress  being  checked  by  a  narrow  lane  i  rod 
wide  and  an  orchard  (E)  4  rods  wide,  thickly  grown  up  with  weeds  and  grass,  which 
separated  A  from  B.  The  chinch-bug  hordes  were  constantly  emerging  from  the 
grass,  however,  and  entering  the  corn.  Many  were  hiding  under  clods  and  rubbish 
in  both  fields,  but  not  one  was  found  dead  with  any  kind  of  fungous  growth. 

Mr.  Wells  reported  August  8,  that,  in  his  opinion,  we  had  wasted  our  labor,  as 
he  could  not  find  any  indication  that  the  disease  had  spread  to  any  part  of  his  farm. 

No.  56.  A  farmer's  contagion  experiment  conducted  by  Mr.  Wells,  and  exam- 
ined several  times  during  the  season  by  Mr.  Marten  and  Mr.  Johnson.  The  box, 
12x18x6  in.,  was  prepared  according  to  our  directions  (see  p.  28),  with  a  bottom  layer 
of  dirt  half  an  inch  deep,  moistened  and  covered  with  a  layer  of  corn  leaves  and  green 
wheat.  About  two  dozen  diseased  chinch-bugs  from  No.  54  were  placed  in  the  box 
June  7,  together  with  a  little  more  than  a  quart  of  live  insects  collected  from  wheat 
and  corn  in  the  neighborhood  of  No.  55.  The  box  thus  stocked  was  tightly  closed, 
covered  with  a  wet  grain  sack,  and  kept  in  the  cellar  on  the  damp  floor. 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  49 

June  10,  nearly  a  quart  of  insects,  both  dead  and  alive,  were  removed  from  the 
box,  several  hundred  of  the  dead  being  well  covered  with  the  fungus.  All  the  insects, 
both  dead  and  alive,  were  used  for  starting  infection  experiments  in  corn  and  oats 
(see  Nos.  57  and  58).  Several  dozen  whitened  bodies  were  left  in  the  box,  into  which 
about  one  pint  of  live  insects  collected  from  corn  (B)  were  put,  together  with  a 
fresh  supply  of  corn  leaves  for  food.  The  box  remained  in  good  condition  and  was 
supplied  with  fresh  food  and  live  insects  about  every  third  day.  June  20  the  second 
lot  of  material  was  removed, — about  three  pints  in  all, — consisting,  as  before,  of  dead 
and  living  insects.  Box  examined  by  Mr.  Marten  and  found  in  excellent  condition; 
several  dozen  bugs  dead  and  covered  with  a  fresh  fungus  growth  left  in  the  box;  fresh 
food  and  about  one-half  pint  of  live  insects  introduced. 

Box  supplied  with  live  insects  and  fresh  food  as  needed.  June  30,  condition  of 
box  about  the  same  as  above.  About  one  quart  of  chinch-bugs  removed  and  placed 
in  corn  (B).  Fresh  food  and  one  pint  of  live  insects  introduced.  The  box  was  left 
undisturbed,  except  when  fresh  food  and  live  insects  were  put  in,  until  the  latter  part 
of  July.  On  one  occasion,  about  the  middle  of  July,  Mr.  Wells  found  a  large  insect, 
which  he  took  to  be  a  cockroach,  under  the  box,  "thickly  covered  with  the  same  white 
fungus."  It  was  removed  and  placed  behind  a  leaf  sheath  on  corn  (B)  among  "a  tea- 
spoonful  of  chinch-bugs,"  and  left  several  days,  without  any  indication  that  the 
disease  spread  to  the  insects  coming  in  contact  with  it.  It  was  afterward  placed  be- 
hind another  leaf,  similarly  covered  with  chinch-bugs,  where  it  remained;  but  at  no 
time  were  there  any  traces  of  the  fungus  on  the  insects  about  it. 

August  i,  the  box  in  good  condition,  and  several  thousand  fungus-covered  bugs 
removed,  together  with  nearly  three-fourths  of  a  quart  of  live  insects,  all  of  which 
were  placed  in  corn  (B),  as  recorded  under  the  following  number.  Fresh  food  and 
about  one  gill  of  live  insects  added;  the  box  set  away  and  not  examined  again  until 
September  19,  at  which  time  it  was  overhauled  by  Mr.  Johnson.  Insects  all  dead; 
the  dirt  in  the  bottom  somewhat  dry,  and  the  food  considerably  moulded;  but  the 
whitened  bodies  of  dead  chinch-bugs  were  very  abundant.  Several  thousand  well- 
covered  specimens  could  have  been  taken  out,  but  the  supply  was  reserved  for  further 
use. 

Mr.  Wells  informed  Mr.  Marten  August  8  that  his  contagion  box  did  not  work 
so  well  after  he  began  putting  in  immature  bugs;  but  that,  altogether,  he  had  dis- 
tributed in  corn  about  four  quarts  of  chinch-bugs  that  had  passed  through  his  box. 

However  successful  this  experiment  may  seem  to  have  been,  it  must  be  borne  in 
mind  that  the  chinch-bugs  introduced  from  time  to  time  had  been  liable  to  infection 
in  the  fields  where  they  were  collected  (see  Nos.  55  and  57),  as  well  as  in  the  con- 
tagion box  itself. 

No.  57.  A  farmer's  field  infection  experiment  made  by  Mr.  Wells  on  his  farm 
near  Farina,  in  corn  (B).  The  first  lot  of  material,  about  two-thirds  of  a  quart  of 
chinch-bugs,  dead  and  alive,  from  his  contagion  box  (No.  56),  was  distributed  June 
10  behind  the  leaf  sheaths  and  on  the  ground  of  the  first,  third,  and  fifth  rows  along 
the  south  and  east  sides,  where  the  bugs  covered  the  first  five  rows  of  corn.  This  field 
was  examined  by  Mr.  Marten  June  19,  but  no  dead  bugs  were  seen,  and  only  a  few 
traces  of  the  original  material  were  found.  The  chinch-bug  attack  was  spreading 
rapidly,  and  corn  was  badly  damaged  throughout  the  south  and  east  parts  of  the  field. 

The  second  distribution  was  made  June  20,  the  material  consisting  of  about  three 
pints  of  chinch-bugs,  dead  and  alive,  from  No.  56.  The  first  three  rows  on  the  south, 
east,  and  west  sides  were  treated  as  above.  Examined  by  Mr.  Wells  June  25.  No 
indications  that  the  disease  was  spreading. 

A  third  distribution  was  made  June  30.  About  one  quart  of  chinch-bugs,  dead 
and  alive,  from  same  source  as  the  others  were  scattered,  as  above,  in  the  second, 
third,  and  fifth  rows  on  the  west  and  north  sides.  Mr.  Wells  examined  field  July  5, 
but  found  no  bugs  dead  with  the  fungus,  save  a  few  scattered  fragments  of  the  orig- 


5O  BULLETIN     NO.    38. 

inal  material.  Mr.  Marten  examined  this(B),  as  well  as  neighboring  fields  (D  and  F), 
July  ii.  No  traces  of  the  disease  were  found  at  this  time  on  this  farm,  except  a  few 
weathered  specimens  in  wheat  (A),  as  noted  in  experiment  55.  All  the  corn  on  this 
farm  was  dwarfed  and  ragged.  The  bugs  were  everywhere  abundant,  covering  the 
stalks  in  many  places  throughout  the  fields. 

The  fourth,  and  last,  distribution  was  made  August  i.  Three-fourths  of  a  quart 
of  chinch-bugs,  dead  and  alive,  from  No.  56  were  distributed,  as  above,  along  the 
west  side  in  the  third,  fifth,  and  seventh  rows,  and  in  three  alternate  rows  through 
the  center  of  the  field.  Mr.  Wells  examined  the  field  August  5,  and  reported  that  he 
could  find  no  signs  of  the  fungus  other  than  a  few  traces  of  the  original  material. 

From  the  above  it  will  be  seen  that  nearly  four  quarts  of  chinch-bugs,  thoroughly 
exposed  to  the  disease,  were  scattered  in  corn  (B),  two  distributions  each  being 
made  on  the  south,  east,  and  west  sides,  one  on  the  north,  and  one  through  the  center 
of  the  field,  as  represented  by  the  heavy  dotted  lines  on  the  plate.  Nevertheless  this 
fungus  practically  disappeared  from  this  farm  during  July  and  August,  and  did  not 
appear  again  until  about  the  middle  of  September.  The  chinch-bugs,  however,  con- 
tinually increased  in  numbers,  and  caused  far  greater  loss  to  corn  than  the  drouth  in 
this  vicinity.  September  4  Mr.  Johnson  found  a  few  traces  of  the  original  material 
along  the  south  and  east  sides  of  the  field  (B).  No  fungus  found  in  corn  marked  D, 
although  live  bugs  were  very  abundant  throughout  the  field.  Nothing  indicating  the 
presence  of  the  white  fungus  was  seen  in  corn  marked  F,  or  in  any  other  field  on  this 
farm,  except  the  one  (B)  just  mentioned.  A  few  bugs  were  found  in  all  the  meadows 
and  pastures  adjoining  corn,  but  all  traces  of  the  local  fungus-outbreak  which  had 
appeared  in  June  had  now  utterly  disappeared. 

Nothing  further  of  importance  was  noted  from  this  neighborhood  until  September 
18,  at  which  time  Professor  Forbes  received  the  following  interesting  letter  from  Mr. 
Wells:  "I  have  been  cutting  corn  and  find  diseased  bugs  scattered  over  the  ground, 
especially  under  stalks  lying  on  the  ground.  I  have  seen  30  or  40  under  a  single 
ear.  I  have  .worked  with  this  disease  with  your  assistants,  and  know  what  I  am 
talking  about.  There  are  still  hordes  of  live  bugs  in  the  field." 

The  field  referred  to  proved  to  be  that  marked  B,  and  was  carefully  examined  by 
Mr.  Johnson  September  19.  The  corn  had  been  cut  and  shocked,  the  work  having 
been  finished  the  previous  day.  The  ground  was  rather  damp,  but  not  muddy  except 
in  the  southeastern  part,  which  is  somewhat  lower  than  the  rest  of  the  field.  There 
had  been  a  heavy  rain  September  4,  and  according  to  Mr.  Wells  a  slight  shower  had 
fallen  about  September  n,  followed  by  a  heavy  rain  again  on  the  i6th.  The  east- 
central,  southern,  and  southeastern  parts  of  the  field  were  rather  weedy,  and  the  corn 
had  fallen  here  much  more  than  elsewhere.  The  weeds,  broken  corn  stalks,  and 
leaves  almost  completely  covered  the  surface  of  the  ground,  which  was  quite  damp 
and  rather  sticky  in  such  places.  Chinch-bugs  had  collected  here  in  considerable 
numbers,  and  whitened  bodies  covered  with  Sporotrichum  were  very  conspicuous 
behind  leaf-sheaths,  on  the  stubble,  on  the  surface  of  the  ground  in  the  open  field, 
under  clods,  bits  of  fallen  leaves,  sticks,  and  rubbish  of  all  kinds;  on  the  ground 
under  weeds  and  grasses;  in  corn  shocks,  on  the  stalks,  behind  the  leaves;  and  on  the 
ground  under  the  shocks.  They  were,  in  fact,  generally  distributed  throughout  the  field, 
being  most  abundant  in  those  portions  thickly  covered  with  weeds,  corn,  etc.,  as  indi- 
cated above.  At  a  point,  f,  under  a  dense  cluster  of  weeds  where  the  ground  was 
quite  damp,  Mr.  Johnson  collected  157  fungus-covered  bugs  from  a  surface  area  of 
two  square  feet;  68  were  counted  at  d  within  a  radius  of  ten  inches,  and  39  were 
found  under  a  single  shock  at  e.  Similar  examples  were  reported  from  all  parts  of 
the  field.  The  great  majority  of  the  insects  attacked  by  this  fungus  were  adults, 
although  several  young  of  the  first  and  second  moults  were  seen. 

Live  chinch-bugs  were  abundant  throughouj  the  stubble,  and  had  accumulated 
in  great  numbers  in  the  shocks;  but  there  was  a  general  movement  in  all  directions 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  c;  I 

into  adjoining  meadows  and  pastures.  The  larger  portion  were  in  the  pupa  stage, 
although  all  ages  were  seen,  even  those  just  emerged  from  the  egg. 

No  traces  of  the  disease  were  found  at  this  time  in  the  wheat  stubble  (A),  and 
only  an  occasional  bug  dead  with  the  fungus  was  seen  in  corn  D.  Seven  whitened 
bodies  were  collected  in  the  vicinity  of/.  The  entire  northwestern  part  of  this  field 
had  been  invaded  by  chinch-bugs  from  wheat  A,  and  was  seriously  injured;  other 
portions  suffered  less  damage. 

In  an  eight-acre  field  of  corn  (F)  to  the  north  of  D  and  east  of  B,  the  chinch-bug 
injury  was  very  much  more  complete  than  in  the  latter,  and  about  the  same  as  in  the 
former.  Dead  bugs  covered  with  Sporotrichum  were  very  numerous,  being  almost,  if 
not  quite,  as  abundant  as  in  B.  The  corn  had  not  been  cut,  and  the  diseased  bugs 
were  found  behind  leaf  sheaths,  under  fallen  stalks  on  the  ground,  around  the  hills 
and  between  the  rows,  and  under  clods,  leaves,  weeds,  grasses,  and  other  rubbish. 
Seventy-eight  whitened  bodies  were  counted  on  the  ground  under  a  single  fallen 
stalk  near  the  center  of  the  field.  Live  bugs,  mostly  adults  and  pupae,  were  every- 
where abundant,  and  completely  blackened  the  corn  in  many  places,  especially 
through  the  central  and  east-central  parts.  According  to  Mr.  Wells'  estimate,  one- 
third  of  the  entire  field  had  been  completely  ruined  at  this  time. 

It  must  be  borne  in  mind  that  not  a  single  diseased  insect  was  artificially  intro- 
duced into  this  field  at  any  time  during  the  season,  and  that  no  traces  of  the  fungus 
were  found  by  Mr.  Johnson  at  the  time  of  his  former  visit,  September  4.  It  seems 
quite  possible,  therefore,  that  the  spores  of  this  fungus  were  quite  as  abundant  in  F 
as  in  B,  and  that  the  parasite  developed  spontaneously  in  both  fields  when  conditions 
fostered  the  growth  of  the  germ. 

All  other  corn  fields  within  a  radius  of  three-quarters  of  a  mile  were  examined, 
but  nothing  was  seen  indicating  the  presence  of  the  fungus.  All  the  corn  seen  was 
badly  damaged,  and  chinch-bugs  were  still  very  numerous. 

Mr.  Johnson  examined  the  fields  in  this  neighborhood  again  September  28.  The 
afternoon  was  very  warm  and  calm,  and  the  air  was  full  of  chinch-bugs  flying  in  all 
directions.  Mr.  Wells  said  that  they  bad  been  flying  in  great  hordes  the  preceding 
day.  The  fungus  was  no  more  abundant  in  the  corn  stubble  (B)  in  the  open  field 
than  at  the  time  of  his  former  visit,  but  the  attack  had  increased  in  the  shocks. 
Fifty-one  chinch-bugs  dead  with  muscardine  were  taken  from  a  surface  area  of  one 
square  foot  under  a  shock  near  the  center  of  the  field  where  the  bugs  were  still  con- 
centrated. Only  a  few  were  seen  in  the  stubble.  Grass  along  the  lane  and  in  the 
orchard  between  B  and  C  was  alive  with  bugs,  but  no  dead  were  seen  among  them. 
The  four-acre  meadow  between  B  and  F  was  damaged  to  a  slight  degree,  and  all  the 
meadows  and  pasture  lands  in  the  immediate  vicinity  of  corn  were  more  or  less 
injured. 

Several  fungus-covered  bugs  were  found  half  a  mile  east  of  the  Wells  farm, 
along  a  dead  furrow,  in  a  field  of  corn  where  the  ground  was  quite  damp  and  the  corn 
considerably  lodged.  No  Sporotrichum  had  been  found  in  this  field  September  18. 
Evidence  of  the  chinch-bug  muscardine  was  also  quite  common  in  low,  damp  places 
in  an  adjacent  field  of  corn.  Five  or  six  whitened  bodies  could  commonly  be  seen 
under  every  fallen  stalk.  About  the  same  condition  existed  in  corn  one-third  of  a 
mile  south  of  the  latter  field.  The  fungus  was  quite  common  in  a  five-acre  corn  field 
west  and  north  of  C,  on  the  opposite  side  of  the  road,  belonging  to  Mr.  Thomas 
Arington.  It  was  easy  to  find  a  dozen  or  more  dead  bugs  covered  with  Sporotrichum 
under  almost  any  piece  of  fallen  herbage,  or  under  pumpkin  vines,  which  were  common 
throughout  the  field.  About  two  and  a  half  acres  of  the  corn  had  been  completely 
destroyed  by  chinch-bugs  coming  from  wheat  on  the  south  side,  leaving  only  an  occa- 
sional stalk  standing  here  and  there.  An  hemipterous  insect  (Nabis  fusca)  imbedded 
in  this  fungus,  was  found  on  the  ground  under  a  cluster  of  grass  by  the  roadside 
opposite  the  northwest  corner  of  C. 


52  BULLETIN    NO.    38.  [March, 

The  disease  was  also  found  in  a  twelve-acre  field  belonging  to  Mr.  A.  C.  Rogers, 
one-half  mile  west  of  the  Wells  farm.  About  half  the  corn  in  the  field  had  been  cut, 
the  greater  part  of  the  remainder  being  flat  on  the  ground.  The  stalks  were  dwarfed, 
the  leaves  dry  and  brown;  and  the  ears  were  little  more  than  soft  cobs,  with  an  occa- 
sional imperfect  grain  attached  to  them.  Chinch-bugs,  mostly  adults  and  pupae,  were 
very  abundant  behind  leaves  at  bases  of  stalks,  where  the  plants  were  somewhat 
green,  and  under  every  cluster  of  grass  about  the  field  In  the  open  field,  where  the 
corn  had  been  recently  cut  and  where  the  ground  was  rather  damp,  eighty-three  dead 
bugs  imbedded  in  this  fungus  were  counted  under  a  single  stalk,  and  whitened  bodies 
could  easily  be  found  under  any  bit  of  rubbish  or  piece  of  herbage  about  the  field. 
Two  fungus-covered  chinch-bugs  were  found  in  a  field  half  a  mile  south,  and  traces  of 
this  fungus  were  found  in  all  other  fields  examined  in  this  vicinity  at  this  time.  From 
the  foregoing,  it  is  clear  that  the  white  fungus  was  generally  present  in  this  neighbor- 
hood, having  been  found  in  all  fields  examined. 

The  final  visit  to  this  section  was  made  by  Mr.  Johnson  and  myself  October  10. 
The  fungus-covered  bugs  were  not  so  abundant  in  the  open  fiejd  (B)  as  formerly, 
although  traces  of  the  disease  were  still  present  on  the  ground  under  grass, 
weeds,  and  rubbish  of  all  kinds;  but  only  an  occasional  dead  bug  was  seen  which  bore 
a'fresh  fungus  growth.  As  a  rule,  dirty  whitish  spots,  scattered  irregularly  over  the 
ground  here  and  there,  were  all  that  remained  of  the  older  examples. 

Very  few  live  insects  were  seen  in  the  corn  stubble  at  this  time.  An  occasional 
cluster  of  foxtail-grass  was  thickly  covered  with  adults  and  pupae,  but  in  such  places 
dead  insects  with  a  fresh  fungus  growth  were  very  rarely  seen. 

The  bugs  were  still  accumulated  in  the  shocks,  especially  along  the  south  side  of 
the  [field;  perhaps  because  this  \vas  the  last  ccrn  cut  and  wes  greener  and  better 
suited  for  food.  In  such  places  fungus- covered  bugs  were  quite  common,  many  of 
them  apparently  just  dead,  as  the  white  cottony  growth  was  just  appearing  en  their 
bodies.  The  fungus  attack,  however,  had  not  increased  since  cur  last  visit,  but  on 
the  other  hand  had  perceptibly  diminished. 

Adults  and  pupae  were  quite  numerous  in  grass  along  the  lane  north  of  B,  but 
were  less  than  half  as  abundant  as  nine  days  previous.  This  reduction  was  probably 
due, to  the  flight  of  the  winged  individuals,  and  not  to  any  contagious  disease,  as  not 
a  single  dead  insect  was  found.  We  did  not  examine  the  fields  D  and  F,  as  Mr.  Wells 
told  us  the  condition  of  affairs  was  about  the  same  as  on  our  previous  visit. 

Sporotrichum  was  generally  present  in  this  region  at  this  time,  as  shown  by  our 
finding  fungus-covered  bugs  in  corn  shocks  and  in  stubble  two  miles  northeast  of 
Farina,  and  in  similar  situations  in  corn  on  the  farm  of  Mr.  R.  H.  Smith,  four  and 
one-half  miles  east  of  the  city.  The  fungus  growth  on  the  bugs  found  at  the  latter 
place  was  fresh,  but  the  disease  had  evidently  been  present  in  the  field  for  some  time 
past,  as  traces  of  old  imaterial  were  easily  detected  on  the  ground,  in  corn  shocks^ 
and  in  the  stubble.  Mr.  Smith  said  that  no  infected  bugs  had  been  distributed  in  the 
neighborhood  of  this  field.  The  occurrence  of  this  disease  seemed  to  be  universally 
spontaneous  at  this  time,  as  we  found  traces  of  it  in  all  the  surrounding  counties. 

Mr.  Wells  wrote  November  20  that  the  disease  was  still  present  in  corn  (B),  and 
reported  having  seen  many  fresh  fungus-covered  bugs  in  corn  shocks  while  husking 
corn  at  that  time. 

With  all  the  facts  before  us  concerning  the  interesting  occurrences  upon  this  farm, 
we'cannot  say  that  our  experiment  was  successful  from  the  economic  point  of  view, 
for  the  muscardine  outbreak  did  not  reach  its  maximum  until  after  the  corn  had 
passed  the  growing  season,  and  it  was  therefore  of  no  practical  use  in  protecting  the 
crop  from  the  ravages  of  the  chinch-bug.  Neither  can  we  say  that  it  was  certainly 
due  to  the  artificial  distribution  of  infected  specimens,  as  the  fungus  was  present  here 
when  the  first  lot  of  dead  chinch-bugs  was  distributed.  (See  No.  55.)  We  must  also 
note  that  an  innumerable  host  of  chinch-bugs  remained  in  the  [corn  -in  a  perfectly 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  53 

vigorous  condition  during  the  entire  dry  period,  which  included  the  latter  part  of 
June,  all  of  July,  and  the  greater  part  of  August;  and  that  the  muscardine  fungus  ap- 
parently disappeared  with  the  advent  of  this  dry  weather,  not  attracting  attention 
again  until  early  in  September,  after  the  fall  rains  had  set  in,  more  than  a  month  and 
a  half  from  the  time  when  the  last  infected  bugs  were  distributed.  Myriads  of  pupae 
and  full  grown  chinch-bugs  were  present,  indeed,  in  the  very  midst  of  the  disease  in 
September,  and  remained  apparently  healthy  and  vigorous  until  winter  came  on.  The 
ratio  of  insects  dead  with  muscardine  to  the  live  ones  present  in  the  field  was  insignif- 
icantly small  to  the  last. 

We  are  also  in  doubt  whether  the  occurrence  of  the  fungus  on  farms  adjacent  to 
that  of  Mr.  Wells  is  to  be  attributed  to  its  spread  from  his  premises,  especially  as  we 
found  it  early  in  October  (from  the  6th  to  the  i3th)  generally  prevalent  in  the  counties 
of  Marion,  Effingham,  Clay,  Jasper,  Richland,  Cumberland,  Bond,  Morgan,  Sanga- 
mon,  and  Champaign.  It  seems  quite  possible,  indeed,  that  its  appearance  on  the  Wells 
farm  itself  was  due  to  the  conditions  that  favored  its  general  development  at  this  time 
throughout  the  greater  part  of  southern  Illinois. 

Finally,  we  have  no  really  positive  assurance  that  its  growth  and  spread  on  Mr. 
Wells'  farm  was  even  hastened  by  his  wholesale  and  persistent  distribution  of  dead 
bugs,  for  the  fungus  was  quite  as  abundant  at  the  same  time  in  far  distant  places, 
where  only  a  few  infected  insects  had  been  distributed  (see  No.  77),  and  in  still  others 
where  no  disease  whatever  had  been  artificially  introduced  (No.  73).  It  was  also  almost 
entirely  absent  in  other  distant  localities,  where  large  quantities  of  both  cultivated 
material  and  infected  insects  had  been  scattered  (Nos.  63,  64,  65,  66,  and  67). 

No.  58.  This  is  also  a  farmer's  field  infection  experiment,  the  last  of  the  series 
conducted  on  the  Wells  farm.  June  10  Mr.  Wells  placed  part  of  the  material  taken 
from  his  contagion  box  (No.  56)  on  that  date  in  the  northwest  corner  of  oats  (C), 
where  chinch-bugs  were  very  numerous,  having  come  from  wheat  on  the  opposite  side 
of  the  road.  The  material,  about  one-third  of  a  quart,  was  scattered  over  the  ground 
between  the  drill  rows,  covering  a  strip  five  or  six  feet  in  width  by  four  or  five  rods  in 
length  (see  heavy  dotted  lines  on  Plate  I).  A  second  distribution,  similar  to  the 
above,  was  made  June  20,  of  several  hundred  chinch-bugs,  dead  with  muscardine, 
taken  from  the  same  box  (56). 

No  traces  of  the  fungus  were  found  in  this  field  June  25,  and  Mr.  Wells  reported 
that  no  disease  was  present  there  July  17,  when  the  oats  were  cut,  although  live 
chinch-bugs  were  everywhere  abundant  in  the  west  half.  Mr.  Johnson  carefully 
searched  the  stubble  and  grass  along  the  road  September  19,  but  found  no  insects 
dead  with  disease;  in  fact,  the  bugs  had  entirely  abandoned  the  field,  except  a  few 
adults  and  pupae  feeding  on  an  occasional  cluster  of  foxtail-grass.  The  grass  along 
the  roadside  was  badly  infested;  but  dead  insects  were  very  rarely  seen.  The  fungus 
was  quite  abundant  in  corn  several  rods  to  the  northwest  September  28,  but  the 
hemipterous  insect  found  at  that  time,  referred  to  in  experiment  57,  was  the  only 
fungus-covered  bug  seen  in  the  immediate  vicinity  of  the  oat  field.  The  experiment  was 
an  utter  failure  so  far  as  the  destruction  of  chinch-bugs  in  the  oats  was  concerned. 

No.  59.  A  farmer's  contagion  experiment  conducted  by  Mr.  James  Smith  on  his 
farm  near  Farina.  About  one  dozen  fungus-covered  chinch-bugs  from  No.  54  were 
delivered  to  Mr.  Smith  June  7  by  Mr.  Marten.  June  8  a  box  was  prepared  according 
to  our  directions,  in  which  a  lot  of  live  chinch-bugs  collected  from  wheat  were 
placed,  together  with  the  bugs  dead  with  Sporotrichum.  The  box  was  supplied  with 
fresh  food  and  live  insects  when  needed.  About  June  15  several  dozen  whitened 
bodies  were  removed  and  placed  in  wheat  (No.  60).  The  box  was  kept  in  good 
condition  until  about  June  27,  when  it  was  abandoned  by  Mr.  Smith,  who  at  that 
time  considered  the  contagious-disease  method  of  "  no  account  in  checking  chinch- 
bug  ravages, "and  resorted  to  the  furrow  method  for  the  arrest  and  destruction  of 
the  bugs  (see  No.  88). 


54  BULLETIN   NO.   38.  [March, 

No.  60.  A  farmer's  field  infection  experiment  made  by  Mr.  James  Smith,  on  his 
farm  near  Farina,  with  several  dozen  bugs  dead  with  the  fungus  from  No.  59,  which 
were  placed  about  June  15  in  a  wheat  field  where  chinch-bugs  were  very  numerous. 
June  19,  field  carefully  examined  by  Mr.  Marten.  First  search  made  in  vicinity  of 
place  where  infected  bugs  had  been  distributed.  A  few  adults  found  here  dead  with 
muscardine,  but  others  also  throughout  the  field  in  about  the  same  proportion.  It 
must  be  borne  in  mind  that  this  same  fungus  was  generally  present  in  this  vicinity  at 
this  time,  being  more  or  less  abundant  in  all  fields  visited.  June  7,  as  noted  under 
No.  55,  it  was  found  in  wheat  on  the  Wells  farm  and  on  other  farms  adjoining  Mr. 
Smith's.  It  is  quite  probable,  therefore,  that  the  fungus  of  the  white  muscardine  of 
the  chinch-bug  was  locally  present  in  the  wheat  where  Mr.  Smith  first  placed  his 
material.  July  n  Mr.  Marten  found  no  traces  of  the  fungus  in  the  wheat  stubble  or 
in  corn  adjoining.  The  disease  practically  disappeared  on  this  place  during  the  very 
dry  weather  of  the  latter  part  of  June,  the  whole  of  July,  and  a  part  of  August,  and 
appeared  again,  in  corn,  late  in  September,  when  it  was  also  generally  present 
throughout  this  region.  Mr.  Johnson  found  several  chinch-bugs  dead  with  this 
fungus  in  an  adjoining  corn  field  on  this  farm  September  18  and  28,  but  no  traces 
were  detected  in  the  wheat  stubble  adjoining. 

No.  61.  June  15.  A  field  infection  experiment  started  by  Mr.  Marten  in  spring 
wheat  on  the  University  farm  (see  B,  Plate  II).  A  quantity  of  dead  and  fungus-bearing 
bugs,  together  with  a  few  live  ones,  all  from  contagion  box  No.  54,  were  scattered  on 
the  surface  of  the  ground  at  the  bases  of  the  wheat  plants  in  the  second  drill  row  for 
a  distance  of  several  rods,  represented  at  c-a,  a  place  where  live  chinch-bugs  were 
most  numerous.  Ground  very  dry,  no  rain  having  fallen  since  June  i,  and  then  only 
.02  of  an  inch.  Sky  clear,  temperature  91°  Fah.*  June  16,  slight  rain  in  the 
afternoon  (.23  inch),  temperature  82°.  June  17,  cloudy,  rain  (.2  inch),  temperature 
82°.  June  18,  cloudy,  temperature  74°.  Examined  by  Mr.  Marten.  Live  bugs  were 
numerous,  and  traces  of  original  material  still  present,  but  no  indication  that  disease 
was  spreading.  June  19,  clear  and  warm,  temperature  81°.  June  20,  light  rain  in 
afternoon  (.1  inch),  temperature  87°.  June  21,  cloudy,  temperature  86°.  Examined 
by  Mr.  E.  B.  Forbes.  Not  the  slightest  indication  that  the  disease  was  spreading, 
only  two  adult  chinch-bugs  being  found  dead  with  fungus  after  a  long-continued 
search,  and  these  apparently  a  part  of  the  original  stock.  Large  numbers  of  young 
bugs  in  all  stages,  with  a  few  adults  intermingled,  feeding  freely  at  the  bases  of  wheat 
plants,  but  no  appearance  whatever  of  the  infection  among  them.  June  22,  slight 
rain  (.05  inch)  in  the  afternoon,  temperature  88°.  June  23,  cloudy,  temperature  90°. 
June  24,  25,  and  26,  considerable  rain  (1.18  inch),  with  average  temperature  82°. 
June  27,  clear,  temperature  88°.  Examined  by  Mr.  Johnson  and  myself.  Plot  closely 
scrutinized  throughout  its  entire  length  and  breadth.  Bugs  very  numerous,  but  none 
dead  with  fungus.  Insects  rapidly  advancing  into  adjoining  corn  (C).  This  same  day 
all  the  earth  from  Nos.  68,  69,  and  70  was  removed,  together  with  several  thousand 
live  bugs  and  many  dead  ones  (about  100  with  the  fungus  and  others  without),  and  all 
scattered  in  the  vicinity  of  the  first  place  of  distribution.  June  28,  29,  and  30,  clear, 
with  high  temperature  (average  89°).  July  i,  light  rain  in  forenoon  (.05  inch), 
temperature  83°.  July  2,  sky  clear,  temperature  85°.  July  3,  forenoon  clear,  after- 
noon cloudy,  temperature  85°.  Experiment  carefully  examined  by  Mr.  E.  B  -Forbes. 
A  few  dead  fungus-covered  chinch-bugs  found  on  ground  in  first  drill  row,  but  no  others 
at  any  point  in  the  field.  Every  wheat  plant  badly  infested  with  bugs  of  all  ages, 
mostly  of  the  last  two  moults.  The  first  three  or  four  rows  of  corn  adjoining  black- 
ened with  pupae,  or  bugs  of  the  moult  just  preceding,  with  an  occasional  adult,  all 
feeding  voraciously  and  apparently  vigorous.  No  trace  of  disease  among  them. 
July  4,  5,  6,  and  7,  clear  and  warm,  with  no  rain,  average  temperature  81°.  Wheat 


Temperature  taken  each  day  at  2  p.  M. 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  55 

cut  on  the  latter  date.  Crop  a  complete  failure;  heads  light  and  grains  very  small 
and  shriveled;  not  gathered  at  all;  burned  over  the  following  day.  Many  chinch- 
bugs  destroyed  by  the  fire  Corn  badly  attacked.  Experiment  a  complete  failure  so 
far  as  the  spread  of  the  disease  was  concerned. 

No.  62.  A  second  field  infection  experiment,  made  June  18  in  the  same  strip  of 
wheat  on  the  University  farm  as  No.  61,  and  under  precisely  similar  conditions 
except  that  the  material  used  consisted  of  about  three  thousand  live  chinch-bugs 
thoroughly  exposed  to  infection  in  No.  54,  and  liberated  by  Mr.  Marten  at  the  point 
represented  at  b,  Plate  II.  Examined  June  21  by  Mr.  E.  B.  Forbes,  June  27  by 
myself  and  Mr.  Johnson,  and  July  3  by  Mr.  E.  B.  Forbes  again,  but  at  no  time  were 
bugs  dead  with  the  white  fungus  found  in  sufficient  numbers  to  indicate  that  the  con- 
tagion had  taken  effect.  On  the  latter  date,  however,  half  a  dozen  fungus-covered 
bugs  were  found  on  the  ground  in  the  first  three  drill  rows,  where  the  original  mate- 
rial had  been  scattered;  otherwise  no  traces  of  the  disease  were  seen,  either  in  wheat 
or  corn.  This  experiment,  like  No.  61,  considered  a  failure. 

The  five  following  (Nos.  63-67)  are  successive  field  infection  ex- 
periments made  on  the  farm  of  Mr.  Samuel  Bartley,  one  mile  west  of 
Edgewood,  in  southwest  Effingham  county,  a  locality  particularly  favor- 
able to  our  purposes,  since  it  was  in  the  midst  of  one  of  the  worst 
infested  districts  of  southern  Illinois.  These  experiments  were  followed 
through  the  season  by  Messrs.  Marten  and  Johnson,  of  the  office  force, 
assisted  by  Mr.  Bartley  on  the  ground.* 

All  the  wheat  fields  on  this  farm,  as  well  as  those  of  the  surround- 
ing neighborhood,  were  closely  examined  by  Mr.  Marten  June  19. 
Young  chinch-bugs  in  all  stages  of  development  were  everywhere 
abundant,  covering  the  wheat  in  many  places,  and  a  few  adults  were 
seen.  In  all  these  fields  small  numbers  of  chinch-bugs,  both  young  and 
old,  were  found  dead  with  the  fungus  of  white  muscardine,  spontan- 
eously occurring.  The  ground  was  rather  moist  at  the  time  from  heavy 
rains  of  the  i6th  and  iyth  of  June,  the  latest  previous  rain  having  fallen 
May  22.  The  temperature  since  this  latter  date  had  been  uniformly 
high,  the  daily  record  rarely  falling  below  90°  Fah.-}* 

No.  63.  June  19,  several  thousand  chinch-bugs  from  No.  54,  some  still  alive  and 
others  dead  with  the  white  fungus,  were  placed  on  the  ground  in  a  small  wheat  field 
on  the  Bartley  farm  where  chinch-bugs  were  most  abundant,  the  exact  location 
being  marked  by  two  stakes  driven  into  the  ground.  Mr.  Bartley  kept  a  record  of 
temperature  and  rainfall,  and  examined  the  field  every  third  or  fourth  day.  June  20, 
21,  22,  and  23  were  exceedingly  hot,  the  average  temperature  reading  for  these  days 
being  96^°  Fah.  No  indications  that  the  disease  was  spreading.  June  24,  light  rain. 
June  25  and  26,  heavy  rains  and  high  temperature  (average  observation,  88°).  No 
dead  seen.  On  the  other  hand,  the  chinch-bug  injury  was  increasing  rapidly,  and 
some  wheat  was  wilting,  with  shriveled  heads.  June  27,  temperature  100°;  wheat  cut 
on  28th  and  2gth;  dry  and  very  hot,  average  midday  temperature,  99°. 

Examination  by  Mr.  Marten  June  29.  Several  fungus-covered  insects  found  in 
drill  rows  where  material  was  placed,  and  a  few  others  a  short  distance  away,  but  as 
a  rule  their  whitened  bodies  were  no  more  numerous  than  before  the  infection  was 


*Mr.  Bartley  has  been  for  several  years  a  correspondent  of  the  office  with  respect  to  the  eco- 
nomic entomology  of  his  district.  He  is  a  man  thoroughly  competent  by  education,  temperament,  and 
experience  to  report  upon  such  matters  as  were  here  entrusted  to  him. 

tThe  temperature  observations  here  reported  were  made  by  Mr.  Bartley  daily  between  eleven 
and  twelve  o'clock. 


56  BULLETIN    NO.    38. 

distributed.  Myriads  of  living  bugs  in  the  stubble,  but  a  general  movement  toward 
adjoining  corn  on  one  side  and  toward  timothy  on  the  other.  June  30,  a  shower; 
temperature  98°.  The  average  midday  maximum  for  the  whole  month  was  94°. 
July  i  to  10,  very  warm  and  dry,  average  midday  temperature,  83^°. 

Field  examined  again  by  Mr.  Marten  July  10.  Wheat  stubble  very  dry, 
yet  containing  matay  live  bugs.  The  great  majority,  however,  have  gone  into  an 
adjacent  corn  field.  No  dead  found  in  stubble,  grass,  or  corn.  The  remainder  of 
July  hot  and  dry.  Good  rain  the  i8th,  and  slight  shower  the  igth.  No  dead  found 
showing  any  traces  of  disease.  Corn  literally  covered  in  many  places.  Light  rain  on 
a8thand2gth.  No  dead  observed.  Very  warm  on  soth  and  3ist,  average  temperature 
record  92°.  Average  midday  reading  for  month,  88°.  First  three  days  of  August 
very  warm,  with  light  rain  the  3d,  followed  by  a  week  of  extremely  hot  weather.  No 
dead  seen. 

Nos.  64  and  65.  August  6,  a  second  infection  experiment  was  begun  by  Messrs. 
Marten  and  Johnson  in  two  of  Mr.  Hartley's  fields  with  material  derived  from  two 
different  sources.  The  first  was  about  three  inches  square  of  a  culture  on  corn  meal 
saturated  with  beef  broth  from  No.  2  (second  remove  from  larva  found  April  17),  and 
the  second  consisted  of  several  hundred  chinch-bugs  dead  with  Sporotrichum  from 
No.  68.  The  corn  was  badly  dwarfed  in  both  fields  and  literally  alive  with  chinch- 
bugs.  Ground  damp,  temperature  88°.  No  trace  of  the  disease  detected  at  this  time 
in  these  fields  or  anywhere  in  the  neighborhood. 

The  cultivated  fungus  (No.  64)  was  placed  in  corn  about  fifty  rods  from  the  spot 
where  the  first  infection  (No.  63)  had  been  introduced  into  wheat.  A  row  along  a  dead 
furrow  was  chosen,  where  the  corn  was  stunted  and  literally  covered  with  chinch-bugs. 
The  culture  material  was  cut  into  small  fragments  and  dropped  into  the  midst  of  the 
bugs  behind  every  sheath  of  twenty-nine  hills,  the  position  being  carefully  marked 
by  cutting  away  the  tassels  from  the  hills  at  either  end. 

The  infected  bugs  (No.  65)  were  distributed  in  an  adjoining  corn  field  thirty-nine 
rods  from  the  wheat  and  fifty  rods  from  the  preceding  distribution  (No.  63).  Condi- 
tion of  corn  about  the  same  as  in  the  foregoing  (No.  64).  Fourteen  hills  on  the  south 
end  of  the  thirteenth  row,  counting  from  the  west  side,  were  treated  and  marked  as 
above. 

The  weather  continued  dry  and  hot  for  the  next  four  days,  the  average  midday 
temperature  being  97^°.  August  u,  heavy  rain,  accompanied  by  extremely  hot 
weather,  the  thermometer  registering  100°.  Both  fields  critically  examined  by  Mr. 
Bartley,  but  no  dead  bugs  seen  and  only  an  occasional  trace  of  the  original  material 
found.  Examined  again  on  the  i7th,  immediately  after  a  slight  shower.  No  fungus 
found.  Corn  in  bad  condition;  ears  shriveled  and  shrunken.  The  high  temperature 
continued,  the  noonday  average  from  the  i2th  to  the  i7th,  inclusive,  being  92°,  and 
that  for  the  month  being  93°.  Light  rains  on  the  23d  and  24th.  Live  bugs  on  the 
increase;  much  corn  fallen  down.  No  dead  bugs,  and  no  indication  that  fungus  had 
spread.  September  4,  very  heavy  rain,  followed  by  high  temperature.  Fields  very 
carefully  examined  by  Mr.  Johnson.  Very  muddy,  and  much  corn  flat  on  the  ground. 
In  such  places,  especially,  the  bugs  literally  covered  every  stalk.  Few  adults  seen, 
the  great  majority  being  of  the  first  or  second  moult  or  pupae.  Only  three  bugs 
dead  with  this  fungus  found  after  a  long-continued  search,  and  these  under  fallen 
corn,  on  the  ground,  a  considerable  distance  from  the  place  where  the  infection 
material  was  placed.  Only  an  occasional  stalk  of  the  hills  originally  treated  remained 
erect,  the  rest  being  dead  and  flat  on  the  ground. 

No.  66.  Conditions  being  now  especially  favorable  to  success,  several  hundred 
spore-covered  bugs  from  No.  68  were  distributed  in  this  field  on  the  Bartley  farm  by 
Mr.  Johnson  September  4,  behind  leaf  sheaths,  and  on  the  ground  under  the  fallen 
stalks  of  twenty-three  hills  which  were  black  with  bugs.  The  location,  which  was 
about  twenty-five  rods  from  that  of  experiment  65,  was  marked  as  before.  September 


1895-]  EXPERIMENTS    WITH    CHIKCH-BUGS.  57 

7,  no  indication  that  the  disease  is  spresding;  a  few  traces  of  the  original  material 
present.  Bugs  everywhere  abundant,  ard  seemingly  healthy.  September  10,  ground 
still  damp,  and  corn  covered  with  bugs,  but  none  dead  with  fungus.  September  18, 
similar  report. 

No.  67.  September  7.  A  second  lot  of  cultivated  fungus  introduced  en  this  date, 
material  from  No.  2  havingjbeen  sent  to  Mr.  Bartley,  who  placed  it,  according  to 
directions,  in  a'one-acre  strip  of  late  corn  near  his  house,  about  eighty  rods  frcm  the 
other  experimental  fields.  The  chinch-bugs  had  accumulated  in  great  numbers  in 
this  late-planted  patch.  Seventeen  hills  of  the  seventh  row,  in  the  southwest  corner, 
were  thoroughly  treated,  as  in  No.  66.  The  ground  was  quite  damp,  and  September 
12,  a  heavy  rain  fell,  followed  by  extremely  hot  weather.  No  dead  bugs  seen  at  this 
last  date,  but  traces  of  infection  material  present  behind  leaf  sheaths  and  on  the 
ground  among  the  bugs.  September  16,  light  rain;  corn  beginning  to  wilt  frcm 
chinch-bug  attack;  not  a  single  dead  insect  seen;  a  little  culture  material  still  present. 

September  18  Mr.  Johnson  carefully  examined  the  Bartley  farm,  and  found  only 
a  single  fungus-covered  insect  in  the  last-mentioned  field.  No  traces  of  the  cultivated 
material.  Corn  about  all  dead,  a  large  proportion  of  it  being  flat  on  the  ground. 
Corn  in  adjoining  fields  all  dead  in  the  immediate  vicinity  of  the  places  where  infec- 
tion experiments  were  made,  and  only  six  bugs  dead  with  the  fungus  found  after  long- 
continued  search.  The  drooping  tassels,  and  the  dirty  brown,  ragged  leaves  hanging 
close  to  the  short  dwarfed  stalks  of  the  remainder,  gave  to  the  whole  neighborhood 
an  aspect  of  desolation.  In  some  places  the  bugs  still  blackened  the  stalks  but  there 
was  a  general  movement  toward  an  adjacent  meadow,  in  which  considerable  damage 
had  already  been  done.  Observations  made  at  later  visits,  did  not  disclose  any  fungus- 
covered  insects  on  this  farm,  and  we  mutt  therefore  class  this  series  of  experiments,, 
Nos.  63-67,  as^absolute  failures. 

The  four  following  (68-71)  are  parallel  laboratory  contagion  ex- 
periments, conducted  at  Natural  History  Hall  in  large  covered  wocden 
boxes,  each  six  feet  long  by  three  wide  and  six  inches  deep,  supplied 
with  a  layer  of  dirt  half  an  inch  deep,  freed  frcm  leaves  and  rubbish 
and  thoroughly  moistened,  the  bottcm  of  each  being  finally  covered 
with  a  layer  of  fresh  green  oats,  or  the  stalks  ard  leaves  of  corn,  for 
food.  Each  box  was  supplied  with  fre^h  food  and  live  insects  as  cir- 
cumstances required,  usually  every  second  or  third  day.  The  period 
of  operations  extended  frcm  June  22  to  September  20,  during  which 
time  a  sufficient  quantity  of  infected  insects  was  taken  out  to  supply 
nearly  two  thousand  applicants  throughout  southern,  central,  and  north- 
ern Illinois,  as  well  asilarge  quantities  used  in  our  own  experiments. 

No.  68.  June  22  a  part  of  the  contents  of'54  were  transferred  to  this  box,  together 
with  a  large  quantity  of  live  chinch-bugs  frcm  the  field.  Everything  was  thoroughly 
moistened  and  the  box  [closed  by  means  of  a  tight-fitting  cover,  screwed  down,  the 
cracks  being  afterwards  pasted  up  with  narrow  strips  of  paper.  Jure  25,  found  no 
very  considerable  development  of  the  fungus.  Large  numbers  of  tugs  dead  which 
showed  no  appearance  of  the  infection.  Ten  of  these  crushed  in  water  on  a  slide  and 
examined  microscopically  contained  no  fungus  mycelium.  One  lot  taken  from  earth 
at  this  time  showed  no  traces  ,of  the  disease;  while  several  otbeis  taken  frcm  coin 
leaves  were  everywhere  penetrated  with  mycelial  threads  of  seme  kind  of  fungus. 
Dead  insects  removed  andoplaced  on  damp  sand  for  further  observation.  Spoiled 
food  removed,  and  fresh^oats  introduced.  June  26,  quite  a  number  of  fungus-covered 
bugs  picked  out  from  food  and  from  surface  of  dirt;  fresh  feed  supplied  and  more 
live  insects.  June  27,  box  in  bad  condition;  all  the  earth,  food,  and  insects  removed. 


58  BULLETIN  NO.  38.  [March, 

Box  cleaned  and  re-stocked  with  fresh  di»t,  food,  and  live  insects.  Several  of  the 
whitened  bodies  taken  out  were  returned  to  the  box.  The  old  material,  dirt,  food, 
insects  and  all,  scattered  in  wheat  (Experiment  61).  June  28,  food  renewed  and  live 
chinch-bugs  introduced.  June  29  and  30,  fresh  food  supplied. 

July  i,  box  in  very  bad  condition;  considerable  mould  on  the  dirt,  and  many  bugs 
covered  with  Aspergillus.  Comparatively  few  covered  with  Sporotrichum.  All  the 
material  removed,  box  washed  out  with  soap  and  water,  thoroughly  burned  over  by 
means  of  a  Bunsen  burner,  and  wet  with  alcohol  and  burned  out  the  second  time.  The 
bottom  covered  with  moist  sand  about  half  an  inch  deep,  fresh  food  introduced,  re- 
stocked with  live  insects,  and  infected  with  fungus-covered  bugs  collected  by  Mr. 
Marten  from  fields  at  Odin  June  22,  and  at  Shattuc  June  23.  July  2,  no  appearance 
of  the  fungus.  July  3,  in  good  condition,  but  no  fungus  developing.  Fresh  food  and 
live  insects  from  reception  box  introduced.  July  4,  very  clean  and  free  from  mould; 
very  little  fungus  present;  growth  not  rapid;  food  changed.  July  5,  fresh  food  and 
live  insects  added.  Anguillulids  noticed  in  abundance  in  the  earth.  July  6,  a  few 
chinch-bugs  with  Sporotrichum.  Fresh  food  and  live  bugs  introduced.  July  8,  no 
bugs  with  fungus  seen.  Box  in  clean  condition.  Four  cicadas,  dead  and  well  covered 
with  this  same  fungus,  collected  at  Mahomet  by  Mr.  E  B.  Forbes,  were  broken  up 
and  the  fragments  distributed  along  the  sides  and  corners  of  the  box  where  live 
chinch-bugs  were  most  numerous.  July  10,  boxes  overhauled  and  cleaned  and  fresh 
food  and  more  bugs  introduced  from  reception  box  A  small  number  of  insects  dead 
with  the  fungus  seen.  July  n,  very  little  Sporotrichum  seen.  Box  in  good  condi- 
tion. Fresh  food  added.  July  12,  fresh  food  introduced.  Box  in  fair  condition. 
July  13,  about  as  yesterday.  July  14,  fungus  scant;  fresh  food.  July  16,  three  or 
four  bugs  with  fungus  seen;  fresh  food  and  live  bugs  introduced,  July  17,  no  fungus 
found.  Part  of  the  food  changed.  July  18,  very  little  fungus  seen.  Fresh  food  and 
more  bugs  introduced.  The  amount  of  water  used  in  box  increased. 

July  19,  about  half  a  dozen  bugs  dead  with  the  fungus.  A  fourth  infection,  coming 
from  No.  n,  a  culture  on  agar,  was  introduced  at  this  time.  July  20,  but  little 
fungus  seen.  Slight  mould  on  earth.  Spoiled  food  removed.  July  21,  box  overhauled 
and  fresh  food  introduced.  Fungus  about  as  yesterday.  July  23,  five  or  six  bugs 
with  Sporotrichum  seen.  The  box  contains  less  mould  than  any  of  the  others  (69,  70, 
and  71)  and  fewest  fungus-covered  insects.  More  live  chinch-bugs  from  reception 
box  added.  July  25,  overhauled  and  food  renewed.  Only  about  half  a  dozen  fungus- 
covered  bugs  seen.  Many  anguillulids  were  found  quite  abundant  on  bugs  dead  with 
and  without  the  fungus,  also  on  the  culture  medium.  A  piece  of  this  material  upon 
which  both  Sporotrichum  and  Aspergillus  were  growing  was  washed  and  found  to 
contain  a  considerable  number  of  anguillulids  both  dead  and  alive,  confined  princi- 
pally to  the  surface,  or  slightly  imbedded  in  the  softer  and  somewhat  decomposed 
spots.  July  26,  Sporotrichum  very  scarce.  July  27,  transferred  contents,  except 
sand,  dead  insects,  and  a  few  live  bugs,  to  No.  69.  Very  little  fungus  seen.  July  30, 
fungus  greatly  increased  165  insects  dead  with  this  disease  removed.  Sand  and 
interior  of  box  thoroughly  wet.  July  31,  quite  a  number  of  dead  bugs  have  a  fresh 
fungus  growth  appearing.  A  few  mites  seen. 

August  i,  seventy  insects  dead  with  Sporotrichum  removed.  Large  numbers  of 
chinch-bug  eggs  found  on  the  sand  and  on  the  older  corn  leaves.  Young  chinch-bugs, 
recently  hatched,  had  been  noted  here  for  several  days.  A  considerable  number  of 
young  insects  also  present.  All  the  sand  removed,  box  scraped  and  brushed,  allowed 
to  stand  until  nearly  dry,  then  wet  with  alcohol  and  burned  out  A  layer  of  fresh 
earth  from  half  to  three-quarters  of  an  inch  deep  placed  in  bottom  and  cultivated 
fungus  on  agar  re-introduced.  The  garden  soil  was  taken  from  five  to  twelve  inches 
below  the  surface,  and  was  free  from  rubbish.  August  2,  all  the  live  chinch-bugs  in 
No.  70  placed  in  this  box.  August  4,  large  number  of  dead  insects,  but  no  fungus 
seen.  Box  in  good  condition.  Fresh  food  introduced.  August  6,  many  bugs  dead 


1895- J  EXPERIMENTS    WITH    CHINCH-BUGS.  59 

with  good  growth  of  fungus  and  many  others  without  it.  Both  Aspergillus  and  mites 
in  small  numbers  on  culture  material.  Food  renewed.  August  9,  a  large  number  of 
dead  insects  developing  Sporotrichum  freely.  A  very  few  mites  and  some  Aspergillus 
found  on  the  culture  material,  much  of  which  was  taken  out  of  the  box.  Food 
renewed.  Several  anguillulids  found  on  dead  insects  in  the  dirt.  August  n,  bugs 
dead  with  the  white  fungus  on  the  increase.  Aspergillus  also  present  in  considerable 
quantities.  A  few  mites  seen  on  culture  material.  Anguillulids  very  abundant,  filling 
the  body  cavities  of  insects  dead  for  a  considerable  length  of  time.  Chinch-bug 
eggs  very  abundant  on  the  culture  material,  some  apparently  about  ready  to  hatch. 
August  15,  condition  of  box  about  the  same  as  when  last  examined.  Sporotrichum 
still  present  in  considerable  quantity.  August  18,  amount  of  fungus  about  the  same. 
Fresh  food  supplied,  box  thoroughly  moistened.  August  22,  many  adults  and  a  few 
young  dead  with  Sporotrichum,  and  several  covered' with  Aspergillus.  Still  another 
greenish  fungus  was  present  on  several  bugs.  Eggs  hatching  by  thousands  in  this 
box.  Mites  increasing,  and  anguillulids  still  present  in  small  numbers.  Fresh  food 
supplied.  August  25,  a  considerable  number  of  insects  dead  with  Sporotrichum. 
Aspergillus  seen  in  small  quantities.  Live  bugs,  mostly  adults,  quite  numerous.  A 
few  young  seen.  Fresh  food  supplied. 

September  3.  Sporotrichum  still  quite  abundant.  Several  hundred  whitened 
bodies  picked  from  the  surface  of  the  earth  and  used  for  experimental  purposes  by 
Mr.  Johnson  at  Edgewood  and  Odin  September  4  and  5  (see  Nos.  66,  73,  and  74).  A 
few  live  bugs  still  present.  Fresh  food  introduced.  September  16,  box  overhauled  and 
fresh  food  added.  About  as  many  fungus-covered  bugs  as  on  last  date.  About 
fifty  dead  with  muscardine  removed  and  used  for  field  infection  experiment  at  Odin 
September  19  (see  No.  73).  Fresh  food  introduced.  September  20,  final  overhaul- 
ing. Several  hundred  whitened  bodies  picked  out,  which  were  distributed  by  Mr. 
Johnson  to  farmers  in  the  south-central  part  of  the  state  early  in  October.  Only  an 
occasional  live  insect  seen.  Box  discontinued. 

No  69  June  23,  a  second  contagion  box,  precisely  similar  to  No.  68,  stocked 
with  a  large  quantity  of  live  chinch-bugs  received  from  correspondents.  The  infec- 
tion introduced  was  from  No.  54.  Examined  June  26;  picked  out  a  few  fungus- 
covered  bugs  and  added  fresh  food  and  chinch-bugs.  June  27,  all  the  material,  dirt, 
bugs,  and  food  removed  and  scattered  in  wheat  (61),  except  a  few  whitened  bodies 
reserved  for  re  stocking  the  box.  Box  thoroughly  cleaned.  June  28,  fresh  food 
supplied  and  a  considerable  number  of  live  bugs  introduced  with  the  fungus-covered 
bugs  removed  yesterday.  June  29,  fresh  earth  introduced,  and  cultivated  spores  on 
agar,  from  No.  n,  added. 

July  i,  very  bad  condition;  earth  covered  with  mould  and  many  dead  insects 
enveloped  in  Aspergillus.  All  the  contents  removed  and  box  thoroughly  disinfected. 
Re-stocked  with  fresh  earth,  fresh  food,  and  live  bugs.  Infected  with  a  number  of 
fungus-covered  insects  collected  by  Mr.  Marten  from  fields  in  the  vicinity  of  Odin 
(June  22)  and  Shattuc  (June  23).  July  2,  fresh  food  added.  July  3,  food  and  an 
additional  lot  of  bugs  introduced.  Box  in  good  condition,  but  no  muscardine 
fungus.  July  4,  fair  condition,  but  little  Sporotrichum.  Food  changed.  July  5, 
about  the  same  as  yesterday,  except  that  many  anguillulids  were  seen.  Fresh  food  and 
more  live  bugs  added.  July  6,  a  little  Sporotrichum  present,  but  not  so  abundant  as 
in  No.  70.  Mould  still  growing  on  earth.  Fresh  food  and  live  insects  introduced. 
July  8,  a  few  bugs  dead  with  the  fungus  removed,  but  the  yield  was  very  poor.  Two 
cicadas  dead  with  this  same  white  fungus,  from  same  source  as  those  used  in  No.  68, 
were  broken  up  and  distributed  along  the  sides,  and  cultivated  fungus  on  agar  from 
experiment  u,  was  scattered  over  the  surface  of  dirt  through  the  middle  of  the  box. 
July  10,  a  little  Sporotrichum  present.  Box  cleaned,  fresh  food  supplied,  and  live 
bugs  from  reception  box  introduced.  July  n,  box  overhauled  and  very  little  fungus 
seen.  Fresh  food  introduced.  July  12,  in  fair  condition;  fresh  food  added. 


60  BULLETIN    NO.    38.  [March, 

Anguillulids  present  in  small  numbers.  Many  bugs  dead,  but  show  no  traces  of  tha 
fungus  on  their  bodies.  Attempts  to  develop  Sporotrichum  on  these  bugs  by  placing 
them  on  damp  sand  proved  failures.  July  13,  condition  about  the  same  as  yesterday. 
July  14,  Sporotrichum  scant.  Box  put  in  good  condition.  Fresh  food  supplied. 
July  16,  only  three  or  four  fungus-covered  bugs  seen.  Moulds  not  so  bad  as  formerly. 
Fresh  food  and  live  insects  from  reception  boxes  added.  July  17,  half  a  dozen, 
ungus-cov  ered  bugs  removed.  Part  of  the  food  changed.  Box  in  fair  condition 
f July  18,  very  little  fungus  seen.  Fresh  food  and  more  live  bugs  introduced,  and  the 
amount  of  water  used  in  moistening  the  box  increased.  July  19,  four  or  five  bugs 
with  Sporotrichum.  Enough  live  insects  taken  out  to  fill  187  pill  boxes,  which 
contained  also  cultivated  Sporotrichum  (from  No.  2)  for  distribution.  Box  in  good 
condition.  July  20,  but  few  fungus-covered  bugs  seen.  Spoiled  food  removed. 
Little  mould  present.  July  21,  fungus  about  as  yesterday.  Fresh  food  introduced. 
July  23,  Sporotrichum  not  very  plentiful.  A  few  bugs  dead  with  the  disease  found 
on  and  in  the  earth.  One  hundred  and  forty-four  pill  boxes  filled  with  live  insects 
and  cultivated  material  (from  No.  2).  More  live  bugs  added.  July  24,  small  number 
of  bugs  with  Sporotrichum  seen.  July  25,  box  overhauled  and  food  changed.  July 

26,  white  fungus  very  scant.    July  27,  very  little  Sporotrichum  seen.     No  anguillulids 
found  in  earth  or  on  dead  insects.     The  contents  of  No    68,  except  sand,  dead  bugs, 
and  a  few  live  insects,  were  transferred  to  this  box.    July  28,  few  fungus-covered  bugs 
seen.    Food  changed.     July  30,  Sporotrichum  increasing,  but  not  abundant.     Asper- 
gillus  also  increasing.     Anguillulids  present  in  small  numbers.     Mites  numerous  on 
earth,  but  not  abundant  on  dead  or  live  insects.     Fresh  food  introduced.     July  31, 
about   fifty   bugs  dead    with   Sporotrichum.     Many   insects   with   Aspergillus   also. 
Moderate   number  of   mites  on  dead   chinch-bugs   and   decayed   vegetable    matter. 
Anguillulids  present  on  dead  bugs  and  dead  coccinellid.     Fresh  food  supplied — about 
one-half  the  quantity  heretofore  used. 

August  3,  final  overhauling  and  cleaning  up.  Bugs  dead  with  Sporotrichum 
estimated  at  about  two  thousand;  many  of  them  pupae,  mainly  on  the  surface  of  the 
dirt.  Most  of  the  hidden  ones  were  under  clods  and  loose  lumps  of  earth.  Quite  a 
number  of  chinch-bugs  were  found  dead  in  copulation,  in  most  cases  both  sexes 
being  infected  with  the  white  fungus.  Occasionally,  however,  only  one  of  a  pair  was 
dead  or  visibly  diseased,  the  other  being  still  alive,  but  unable  to  free  itself.  Two 
instances  were  noted  where  one  of  each  pair  was  dead  and  covered  with  Aspergillus, 
while  the  other  showed  no  growth  of  any  kind.  Mites  still  present,  but  considerably 
less  numerous  than  before.  Live  chinch-bugs  were  not  abundant,  those  remaining 
being  mostly  adults,  with  very  few  pupae,  young  of  the  first  and  second  moult, 
and  numbers  of  eggs.  Box  discontinued. 

No.  70.  June  23,  a  third  box,  similar  to  No.  68  and  69,  was  stocked  with  food  and 
large  numbers  of  chinch-bugs  received  from  correspondents,  but  not  infected.  June 

27,  thoroughly  overhauled;  earth  supplied;  new  food  and  more  live  bugs  introduced. 
Infected  with  fungus-covered  bugs  from   experiments  68  and  69.     June  28,   food 
renewed  and  more  live  bugs  added.     June  29  and  30,  fresh  food  introduced. 

July  i,  mould  on  surface  of  earth,  box  in  very  bad  condition.  Aspergillus 
present  on  several  dead  bugs.  Comparatively  little  Sporotrichum.  Box  thoroughly 
cleaned  and  disinfected;  earth  renewed,  fresh  food  added,  and  live  insects  introduced. 
July  2,  no  fungus  seen.  July  3,  in  good  condition,  but  no  Sporotrichum  seen.  Fresh 
food  and  more  bugs  introduced.  July  4,  in  fair  condition.  A  few  insects  with  fresh 
fungus  growth  on  their  bodies.  Food  changed.  July  5,  condition  about  as  yester- 
day, except  that  anguillulids  were  noticed  quite  abundant  in  earth.  Food  changed 
and  more  live  insects  added.  July  6,  white  fungus  more  abundant  than  in  experiment 
69.  Mould  on  dirt  still  spreading.  Fresh  food  and  more  bugs  added.  July  8,  a  few 
chinch-bugs  dead  with  white  fungus  removed.  Earth  stirred  to  destroy  mould.  Box 
in  fair  condition.  A  second  infection  introduced.  Two  cicadas  from  same  source 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  6l 

as  those  used  in  Nos.  68  and  69,  were  broken  up  and  distributed  over  the  surface  of 
the  dirt,  along  the  middle  of  the  box,  and  a  quantity  of  cultivated  material  from  No. 
2  was  distributed  around  the  sides.  July  10,  a  few  fungus-covered  bugs  removed. 
Dirt  contains  much  mould.  Aspergillus  less  abundant  than  previously.  Box  cleaned 
up  and  fresh  food  introduced.  July  n,  very  little  fungus  seen.  Fresh  food  added. 
July  12,  little  Sporotrichum  present.  Anguillulids  seen  in  dirt.  Many  bugs  dying, 
but  without  developing  Sporotrichum.  Fresh  food  introduced.  July  13,  about  same 
condition  as  yesterday.  July  14,  Sporotrichum  scant,  but  more  abundant  than  in  Nos. 
68  and  69.  Fresh  food  added.  July  16,  thirty-six  fungus-covered  bugs  picked  from 
surface  of  dirt,  and  afterwards  returned.  Moulds  not  so  bad  as  formerly.  Fresh  food 
and  more  bugs  from  reception  box  added.  July  17,  no  fungus  of  any  consequence 
present.  Spoiled  food  removed.  July  18,  very  little  Sporotrichum  seen,  but  more 
abundant  than  in  other  boxes  (68,  69,  and  71).  Food  changed  and  amount  of  water 
used  in  the  box  increased.  July  19,  fungus  more  abundant  than  in  68  and  69.  Box 
in  good  condition.  July  20,  very  few  fungus-covered  bugs  seen.  Removed  enough 
live  bugs  for  three  hundred  pill  boxes,  with  cultivated  fungus  (from  No.  2),  for  ship- 
ment. A  little  mould  present  on  earth.  Old  food  removed.  July  21,  fungus  about 
as  abundant  as  yesterday.  Box  in  good  condition.  Fresh  food  introduced.  July  23, 
few  bugs  with  fungus  seen.  One  hundred  and  forty-four  pill  boxes  filled  with  live 
insects  and  cultivated  fungus  from  same  source  as  above,  and  prepared  for  shipment. 
Large  number  of  live  bugs  from  reception  box  introduced.  July  24,  fungus-covered 
bugs  more  abundant,  but  not  numerous.  Anguillulids  present  on  dead  chinch-bugs. 
July  25,  overhauled  and  food  renewed.  July  26,  Sporotrichum  very  scant;  the 
living  bugs  from  experiment  71  transferred  to  this  box.  Anguillulids  found  in 
earth  and  on  corn  leaves  in  small  numbers.  July  28,  few  bugs  with  Sporotrichum 
seen.  Fresh  food  introduced.  July  30,  number  of  bugs  with  fungus  not  great. 
Aspergillus  on  the  increase.  Mites  abundant  on  the  earth.  Anguillulids  present  on 
dead  pupae  and  adults.  The  worms  were  present  on  a  dead  pupa  which  contained  an 
apparent  mycelial  growth  of  the  white  fungus.  Two  adults,  dead  and  badly  decom- 
posed, contained  them  in  considerable  numbers.  July  31,  about  fifty  insects  dead 
with  the  white  fungus  seen,  but  growth  very  poor,  in  most  cases  being  quite  incon- 
spicuous. Mites  very  abundant  on  the  corn,  especially  where  the  sap  was  exuding. 
A  few  were  seen  on  dead  chinch-bugs  behind  corn  leaves.  Anguillulids  were  also 
seen  on  dead  bugs  in  similar  situations.  Old  food  removed,  and  about  half  the 
quantity  of  fresh  food  usually  introduced  was  added. 

August  2,  two  hundred  and  eighty-one  fungus-covered  insects  removed.  Among 
hem  a  pair  copulating,  the  female  being  dead,  with  a  short  mycelial  growth  about  the 
thoracic  region,  while  the  male  was  still  alive,  quite  active,  and  showed  no  signs  of 
distress  or  irritation.  Chinch-bug  eggs  and  young  were  abundant.  Ten  blow-fly 
larvae  were  seen.  Mites  very  abundant,  sometimes  accumulating  in  great  numbers 
on  the  leaves.  Box  finally  overhauled;  everything  removed  and  transferred  to  No.  68. 

No.  71  June  26,  the  fourth  large  box  was  supplied  with  earth,  and  stocked  with  live 
chinch-bugs  and  fresh  food,  but  no  infection.  June  27,  fresh  food  introduced.  June 
28,  food  renewed  and  a  lot  of  live  bugs  added.  Infected  with  cultivated  spores  on 
corn  meal  and  beef  broth  (from  No.  2).  June  29,  fresh  food  introduced.  July  i,  in 
iair  condition.  Cleaned  up.  Fresh  food  and  more  live  insects  added.  July  2,  very 
little  Sporotrichum  seen.  A  little  mould  on  the  earth.  Fresh  food  introduced.  July 
3,  enough  fungus-covered  bugs  removed  to  make  up  forty-nine  boxes  for  correspond- 
ents. Little  mould  on  earth.  More  live  bugs  added.  July  4,  fungus  quite 
abundant,  the  whitened  bodies  of  the  insects  being  most  abundant  just  beneath  the 
surface  of  the  earth.  Material  for  thirty-eight  packages  removed.  Earth  in  box 
stirred  up  to  destroy  moulds.  Fair  condition.  Food  changed.  July  5,  condition 
about  as  yesterday,  except  that  a  few  anguillulids  were  seen  in  earth.  July  6,  a  few 
fungus-covered  bugs  present.  Moulds  still  developing  on  earth.  Fresh  food  and 


62  BULLETIN   NO.  38.  [March, 

live  insects  added.  July  8,  very  little  Sporotrichum  seen.  Box  in  very  bad  condition. 
Aspergillus  quite  abundant  on  dead  bugs,  and  moulds  common  on  the  earth.  Blow-fly 
larvae  very  numerous.  Food  changed  and  live  bugs  introduced.  July  10,  only  slight 
traces  of  muscardine.  Aspergillus  seems  less  abundant.  Moulds  still  present.  Fresh 
food  added  and  more  chinch-bugs  from  reception  box  introduced.  July  n,  few  bugs 
dead  with  Sporotrichum.  Box  in  fair  condition.  Fresh  food  and  more  live  insects 
added.  July  12,  in  fair  condition.  Anguillulids  present  on  earth.  Many  bugs 
dying  without  developing  any  sort  of  fungus  growth.  Fresh  food  introduced.  July 
13,  condition  about  the  same  as  yesterday.  Anguillulids  present  in  small  numbers. 
July  14,  Sporotrichum  very  scant.  Food  changed.  July  16,  only  two  insects  dead 
with  muscardine  seen.  Moulds  on  earth  not  so  bad  as  formerly.  Fresh  food  and  an 
additional  lot  of  bugs  from  reception  box  introduced.  July  17,  no  Sporotrichum  of 
any  consequence  seen.  Fresh  food  added.  July  18,  white  fungus  very  scant.  Fresh 
food  added.  Amount  of  water  used  in  moistening  box  increased.  July  19,  a  greater 
number  of  insects  dead  with  muscardine  than  were  seen  in  experiments  68  and  69  on 
this  date,  the  number  dead,  however,  being  about  equal  to  those  in  No.  70.  Box  in 
good  condition.  July  20,  very  few  fungus-covered  bugs  seen.  Bad  food  removed. 
Slight  traces  of  mould  on  earth.  July  21,  amount  of  fungus  about  as  yesterday.  One 
hundred  and  thirty-two  pill  boxes  filled  with  live  bugs  and  cultivated  material  (from 
No.  2),  and  prepared  for  shipment.  Box  thoroughly  overhauled  and  fresh  food 
introduced.  July  23,  more  bugs  from  reception  box  introduced.  July  24,  bugs  with 
Sporotrichum  few  in  number.  Anguillulids  quite  plentiful  on  dead  insects.  July  25,  box 
overhauled  and  food  renewed.  July  26,  white  fungus  very  scant.  A  quantity  of  living 
bugs  transferred  from  this  box  to  No.  70.  Anguillulids  found  quite  abundant  on  the 
earth.  July  30,  final  overhauling.  No  Sporotrichum  found.  Many  dead  insects 
covered  with  Aspergillus.  Mites  very  abundant  on  earth,  and  their  eggs  found  on  a 
dead  chinch-bug  enveloped  in  a  growth  of  Aspergillus.  Box  discontinued. 

No.  72.  An  experiment  begun  June  i  to  test  the  direct  effect  of  moisture  upon 
chinch-bugs  in  confinement.  A  number  of  specimens  from  Tonti,  in  southern  Illi- 
nois, which  had  not  been  exposed  to  fungous  infection,  were  placed  in  a  Riley  breeding- 
cage,  the  top  of  which  was  afterwards  covered  with  glass  to  prevent  evaporation. 
This  cage  sat  in  a  metal  pan,  the  bottom  of  the  cage  being  filled  with  earth.  Water 
was  poured  into  the  pan  outside  of  the  cage,  and  kept  standing  there  continuously  to 
insure  the  saturation  of  the  earth  and  the  air  inside  the  cage, 

June  2,  water  stood  in  drops  on  the  sides  of  the  cage  and  on  corn  and  grass 
within.  June  4,  no  losses  among  the  chinch-bugs.  June  9,  many  of  the  bugs  dead, 
but  with  no  trace  of  fungus  growth.  June  13,  adults  now  all  dead,  but  with  no 
appearance  of  disease;  young  still  in  good  condition;  earth  saturated  and  moisture 
standing  in  drops  on  plants  and  all  over  the  inside  of  the  breeding  cage.  June  15, 
only  a  very  few  young  bugs  left  alive,  none  having  shown  fungous  disease  at  any  time. 
Between  this  and  July  3,  those  remaining  died;  and  at  the  latter  date,  when  the  cage 
was  overhauled,  no  growth  of  a  fungus  parasite  had  appeared  on  these  specimens. 

The  two  following  (Nos.  73  and  74)  are  successive  field  infection 
experiments  conducted  by  Mr.  Johnson  near  Odin,  in  Marion  county,  a 
district  especially  favorable  for  experimental  work, -each  being  followed 
up  by  repeated  visits,  from  August  7  to  October  6. 

No.  73.  August  7,  several  hundred  fungus-covered  bugs  from  No.  68,  were 
placed  behind  leaf  sheaths  and  on  the  ground  in  a  field  of  late  corn  on  the  farm  of 
Mr.  Thomas  Ferguson,  Sr.,  one  mile  north  of  Odin.  The  spot  chosen  was  especially 
favorable  to  the  growth  of  the  white  fungus,  being  along  a  dead  furrow  in  a  low, 
damp  place  where  the  corn  was  much  dwarfed  and  completely  covered  with  chinch- 
bugs,  which  had  come  largely  from  an  adjoining  wheat  field.  No  fungus-covered 
insects  were  seen  here  at  the  time. 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  63 

Every  hill  on  the  west  end  of  the  twenty-third  row,  counting  from  the  south 
side,  was  treated  with  spores  of  muscardine  for  a  distance  of  thirty  paces  The 
tassels  were  cut,  marking  the  east  and  west  boundaries.  Chinch-bugs,  both  young 
and  old,  were  very  abundant;  adults  were  copulating;  and  young  just  past  the  first 
moult  reddened  the  stalks. 

This  field  was  examined  by  Mr.  Johnson  September  5.  Very  heavy  rain  had 
fallen  the  day  before,  and  the  field  was  very  muddy.  No  traces  of  disease  were  found, 
except  a  single  fungus-covered  insect  behind  a  leaf.  The  corn  was  nearly  destroyed 
by  the  chinch-bugs,  and  flat  on  the  ground  in  many  places,  especially  in  that  part  of 
the  field  where  the  infection  material  had  been  distributed.  Only  five  or  six  stalks 
of  the  hills  treated  remained  standing.  Stalks  flat  on  the  ground  and  not  dead  were 
literally  covered  with  live  bugs.  Other  parts  of  the  field,  where  the  corn  was  most 
vigorous,  and  where  the  bugs  were  least  abundant  on  our  former  visit,  were  now 
overrun  with  the  chinch-bug  hosts;  in  one  place  about  two-thirds  of  a  pint  were 
collected  from  two  hills,  by  jarring  and  shaking  them  over  a  cloth  spread  on  the 
ground.  The  insects  were  very  active,  and  apparently  in  a  healthy  condition. 

At  this  date  (September  5)  Mr.  Johnson  placed  a  second  lot  of  infected  bugs 
from  experiment  68  in  this  field,  where  the  conditions  were  especially  favorable. 
The  ground  was  very  wet  and  the  corn  much  lodged  and  covered  with  chinch-bugs. 
About  one  hundred  bugs,  dead  with  the  white  fungus,  were  scattered  behind  corn 
leaves,  about  forty  rods  from  the  place  where  the  first  infection  material  was 
introduced. 

September  19,  Mr.  Johnson  carefully  examined  this  field  again.  Corn  had  been 
cut,  where  it  was  worth  saving  at  all,  and  shocked.  The  bugs  were  thickly  concen- 
trated in  the  shocks,  but  no  traces  of  muscardine  were  seen  among  them.  The 
insects  were  still  very  abundant  in  the  stubble.  The  corn  in  many  places  was  as  flat 
on  the  ground  as  if  a  roller  had  gone  over  it,  and  in  such  places  every  stalk  was 
blackened  with  bugs.  A  third  lot  of  chinch  bugs,  about  fifty  in  all,  dead  with 
Sporotrichum  from  the  same  source  as  the  others  (No.  68),  were  now  scattered  over 
the  ground  under  the  fallen  corn,  at  one  place  about  ten  rods  from  the  row  where  the 
second  lot  of  bugs  had  been  placed.  The  greater  part  of  the  corn  on  the  ground  was 
brown  and  dead,  and  there  was  a  general  movement  of  the  chinch-bug  hordes  into 
late  corn  in  an  adjoining  field  on  the  west,  and  into  a  meadow  touching  the  south- 
west corner.  Considerable  damage  had  been  done  by  the  insects  to  the  grass  in  the 
latter  field,  and  corn  in  the  former  was  suffering  severely  from  their  attacks.  Not  a 
single  diseased  bug  was  found  in  any  of  these  fields  at  this  time. 

Examined  by  Mr.  Johnson  September  26.  Very  few  chinch-bugs  in  the  stubble. 
One  bug  found  imbedded  in  the  white  fungus.  Many  insects  in  the  meadow.  The 
late  corn  in  the  field  adjoining  the  stubble  badly  damaged,  the  attack  apparently 
increasing.  No  traces  of  disease  seen  in  this  field.  Bugs  seemingly  vigorous  and 
healthy. 

The  final  visit  of  the  season  to  this  locality  was  made  by  Mr.  Johnson  October 
6.  At  this  time  the  late  corn  in  the  field  last  mentioned  in  the  preceding  paragraph  had 
been  cut  and  shocked  about  a  week,  and  the  ground  planted  in  wheat.  The  bugs  had 
accumulated  in  enormous  numbers  in  the  shocks.  Half  a  dozen  fungus-covered 
insects  were  taken  from  shocks  in  this  field  at  various  places,  and  several  were  taken 
from  grass  in  the  adjoining  meadow,  where  the  chinch-bug  attack  was  still  spreading. 
A  dozen  or  more  whitened  bodies  were  taken  from  shocks  and  under  fallen  corn  in 
the  held  where  the  infection  had  been  distributed,  but  the  fungus  was  nowhere  abun- 
dant, and  long-continued  search  was  required  to  find  even  a  single  specimen.  A  few 
live  chinch-bugs,  mostly  adults  and  pupae,  were  still  present  in  the  stubble,  and  bugs 
in  the  same  stages  were  quite  abundant  in  the  shocks.  Corn  in  both  these  fields  was 
a  complete  failure,  and  was  saved  for  fodder  only.  Chinch-bugs  dead  with  the  white 
fungus  were  found  in  all  fields  examined  in  this  county  at  this  time,  but  only  in  two 


64  BULLETIN    NO.    38.  [March, 

places  (Nos.  57  and^6)  ware  they  at  all  common,  and  even  here  the  live  bugs  out- 
numbered the  dead  many  thousand  times.  This  experiment  for^the  introduction  and 
increase  of  the  fungus  by  artificial  means  was  to  all  appearance  a  complete  failure. 

No.  74.  August  7,  the  second  of  this  series  of  experiments  was  begun  in  a 
twenty-acre  corn  field  (B,  Piate  IV)  owned  by  Mr.  Silver,  of  Cincinnati,  Ohio,  and 
planted  by  Mr.  Frank  Robinson,  of  Odin.  This  farm  is  about  a  mile  and  a  half 
north  of  Odin,  between  the  Ferguson  farm  on  the  south  (No.  73)  and  the  Hurd  and 
Robinson  farms  on  the  north  (Plate  IV).  The  field  was  very  dry  and  dusty;  the  corn 
thin,  short,  and  very  poor.  Chinch-bugs  just  past  the  first  moult  covered  nearly 
every  stalk.  A  few  adults  ware  seen  copulating.  No  traces  of  the  fungus  disease 
were  seen. 

A  row  of  dwarfed,  sickly  looking  corn  along  a  dead  furrow  about  the  center  of 
the  field,  thickly  covered  with  bugs,  was  selected  as  a  suitable  place  for  the  introduc- 
tion of  the  infection.  A  piece  of  culture  material  from  No.  2,  about  two  inches  wide 
by  four  inches  long,  containing  a  profuse  growth  of  Sporotrichum,  was  cut  into  small 
fragments  and  placed  among  the  bugs  behind  the  leaves  of  every  hill,  for  a  distance 
of  fifty  paces,  the  spot  being  marked  by  clipping  the  tassels  from  the  hills  at  either 
end. 

Examined  August  18  by  Mr.  Johnson.  No  fungus-covered  insects  found.  Some 
of  the  culture  material  still  present.  Corn  in  very  bad  condition  and  flat  on  the 
ground  in  many  places.  Chinch-bugs  cover  the  corn  throughout  the  field.  Foxtail  and 
other  grasses  literally  alive  with  the  insects.  Weather  very  dry  and  hot. 

Second  examination  September  5,  immediately  after  very  heavy  rain.  Field  very 
muddy.  No  traces  of  the  infection  material  visible,  and  no  bugs  dead  with  the  fungus 
seen.  Corn  crop  an  utter  failure.  Chinch-bugs  seem  to  be  increasing  in  numbers. 
Selected  another  row  along  a  dead  furrow,  about  five  rods  from  the  first,  and  distribut- 
ed about  one  hundred  fungus-covered  bugs  from  experiment  683behind  the  leaves 
for  a  distance  of  seventy-three  paces,  and  marked  as  before. 

September  19,  not  a  single  insect  dead  with  the  white  fungus  found  in  this  field 
after  an  hour's  diligent  search.  Corn  about  all  dead.  Chinch-bugs  still  very  abun- 
dant, but  many  g  Ding  into  meadows  on  the  north  and  east.  Few  adults  seen  flying. 
September  26,  about  as  before,  except  that  the  corn  is  all  dead  and  chinch-bugs 
less  numerous.  No  dead  seen,  and  not  a  trace  of  the  fungus  found.  Chinch-bugs 
very  abundant  in  the  adjoining  meadows,  and  considerable  grass  killed. 

The  final  visit  for  the  season  was  made  October  6.  About  one-fourth  of  the  corn 
had  been  cut  and  shocked  and  saved  for  fodder;  the  other  three-fourths  was  flat  on 
the  ground,  dead  and  brown.  Chinch-bugs,  mostly  adults  and  pupae,  were  quite 
numerous  in  the  shocks,  and  on  the  fallen  corn  throughout  the  field.  Half  a  dozen 
bugs  dead  with  Sporotrichum  were  picked  up  on  the  ground  under  a  corn  shock  about 
two  rods  from  the  place  where  the  last  lot  of  infection  material  had  been  introduced, 
and  a  few  others  were  found  at  various  points  in  the  field,  under  shocks  and  fallen 
corn,  but  this  was  all.  The  presence  of  the  fungus  on  chinch-bugs  in  this  field  at 
this  time  did  not  seem  to  have  any  connection  with  that  distributed  August  7  and 
September  5,  since  the  disease  was  found  more  or  less  prevalent  in  all  fields  visited  in 
this  neighborhood  at  this  time.  As  the  white  muscardine  did  not  spread  from  the 
centers  where  the  infection  was  introduced,  and  as  the  chinch-bug  hosts  continually 
increased,  remaining  in  a  vigorous  and  perfectly  healthy  condition  in  its  very  midst, 
the  experiment  is  regarded  as  a  complete  failure. 

This  description  should  be  read,  however,  in  connection  with  that  given  under 
No.  76,  relating  to  a  considerable  outbreak  of  chinch-bug  muscardine  on  a  farm  im- 
mediately adjoining  this  upon  the  north. 

No.  75.  This  is  a  farmer's  field  infection  experiment  made  by  Mr.  Frank  H. 
Robinson  on  his  farm  (the  right  hand  third  of  Plate  IV.),  about  two  miles  north  of 
Odin.  August  7,  several  pieces  of  culture  material  containing  a  profuse  growth  of 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  65 

the  white  fungus,  from  No.  2,  were  placed  in  Mr.  Robinson's  hands  by  Messrs. 
Marten  and  Johnson,  and  directions  given  for  its  distribution.  August  8,  two  small 
plats  of  corn,  represented  on  Plate  IV.,  at  C  and  D,  thickly  covered  with  chinch-bugs, 
were  chosen  and  the  infection  material  scattered  along  the  north  side  next  the 
orchard,  behind  the  leaves  and  on  the  ground  at  the  bases  of  the  stalks  where  the 
insects  were  most  abundant. 

September  5,  examined  by  Mr.  Johnson.  Corn  all  dead  in  plat  represented  at  D. 
Chinch-bugs  still  very  abundant  on  the  dead  brown  stalks  and  leaves.  No  traces  of 
the  infection  material  found,  and  only  two  bugs  dead  with  this  fungus  were  seen;  and 
these  were  taken  from  under  a  clod  on  the  ground,  which  was  very  wet  from  recent 
heavy  rains.  About  the  same  condition  was  noted  in  plat  C,  except  that  a  few  traces 
of  the  old  culture  material  still  remained  on  the  ground  at  the  bases  of  a  few  stalks, 
and  that  no  fungus-covered  bugs  were  seen.  Chinch-bugs  were  present  in  small 
numbers  in  all  the  meadows  bordering  the  field  containing  this  corn.  In  a  twenty- 
two-acre  field  north  of  the  house,  represented  at  E,  the  corn  was  completely  destroyed 
by  their  attacks,  and  nothing  green  remained.  The  bugs  were  everywhere  abundant, 
and  almost  completely  covered  the  ground  in  many  places,  but  there  were  no  traces 
of  fungous  disease.  Grass  in  the  meadow  adjoining  on  the  south  was  slightly 
damaged. 

September  19,  a  few  live  bugs,  mostly  adults  and  pupae,  were  seen  in  the  stubble 
at  C  and  D,  but  no  traces  of  Sporotrichum  were  found.  The  insects  were  still 
present  in  the  surrounding  meadows.  The  corn  ground  (E)  had  been  planted  in 
wheat,  and  only  a  few  bugs  remained  in  the  field.  The  attack  had  greatly  increased 
in  the  meadow  to  the  south,  and  considerable  grass  had  been  killed.  No  traces  of  the 
white  fungus  seen  on  this  place  at  this  time.  September  26  and  October  6,  similar 
report  made  by  Mr.  Johnson,  except  that  a  few  fungus-covered  bugs  were  found  in 
the  meadow  south  of  E,  on  the  latter  date.  The  experiment  is  classed  with  73  and  74 
as  a  total  failure. 

This  description  should  be  read,  however,  in  connection  with  that  given  under 
76,  relating  to  a  considerable  outbreak  of  chinch-bug  muscardine  on  a  farm 
immediately  adjoining  this  on  the  west. 

No.  76.  This  is  the  second  of  the  three  exceptional  cases  of  spontaneous  muscar- 
dine, referred  to  above.  It  appeared  on  the  farm  of  Mr.  Silas  Kurd,  about  one  and 
a  half  miles  north  of  Odin,  in  the  corn  field  marked  A,  Plate  IV.  This  field  of  forty- 
nine  acres  was  planted  early  and  grew  rapidly  for  a  time,  but  then  came  practically 
to  a  stand  on  account  of  incessant  chinch-bug  attack  and  the  drought  which  prevailed 
throughout  that  region  during  the  latter  part  of  the  summer. 

The  corn  was  cut  and  shocked  while  yet  in  roasting  ears,  early  in  September,  in 
order  to  save  the  fodder,  and  the  field  was  deeply  harrowed  and  planted  to  wheat. 
No  Sporotrichum  had  been  distributed  in  this  field  at  any  time;  but  unsuccessful 
attempts  to  infect  fields  had  been  made,  as  described  under  Nos.  74  and  75,  on  the 
Robinson  and  Silver  farms  at  distances  of  a  little  more  than  a  quarter  of  a  mile 
away.  (See  B,  C,  and  D,  Plate  IV.) 

Mr.  Johnson  examined  this  field  October  6,  and  found  the  white  fungus  quite 
abundant  in  all  the  shocks.  One  hundred  and  fifty-two  dead  chinch-bugs  imbedded 
in  it  were  collected  in  a  few  minutes  from  a  single  shock  at  a,  and  every  shock 
examined  in  the  southern  and  western  parts  of  the  field  contained  fungus-covered 
bugs  in  considerable  numbers.  At  b,  in  the  northeastern  part,  it  was  an  easy  task  to 
collect  several  hundred  whitened  bodies  in  and  under  every  shock.  This  part  of  the 
field  was  quite  low,  and  chinch-bugs,  mostly  adults  and  pupae,  had  accumulated  in 
the  shocks  in  enormous  numbers.  This  was  perhaps  due  to  the  fact  that  all  green 
vegetation  in  the  field  had  been  destroyed  by  the  harrow  and  cultivator,  and  that  the 
bugs  were  obliged  to  congregate  in  the  shocks  or  to  leave  the  field  in  search  of  other 
food. 


66  BULLETIN    NO.    38.  \_Mdrch, 

Only  an  occasional  fungus-covered  insect  was  found  in  a  field  of  sweet  corn  (F) 
which  had  been  completely  ruined  by  chinch-bugs,  and  which  was  not  cut  at  all. 
Adults  and  pupae  were  still  present  there,  but  not  very  abundant.  Bugs  were  seen 
in  small  numbers  in  all  the  green  lands  surrounding  the  corn  (A);  but  no  traces  of 
the  fungous  disease  were  found,  with  the  exception  of  three  or  four  dead  insects  taken 
from  grass  in  the  meadow  next  the  road  east  of  A.  A  few  others  imbedded  in  Sporo- 
trichum  were  found  in  corn  (B),  as  noted  in  experiment  74,  and  several  were  taken 
from  grass  in  the  meadow  west  of  corn  field  E,  as  stated  in  No.  75. 

The  fact  that  this  fungous  disease  was  almost  totally  absent  in  fields  surrounding 
A,  would  seem  to  indicate  that  it  must  have  been  fostered  in  the  latter  field  by 
especially  favorable  conditions.  These  seem  to  have  been  (i)  the  early  cutting  and 
shocking  of  the  corn  while  it  was  still  green;  (2)  the  destruction  of  all  food  through- 
out the  open  field,  such  as  grasses  of  various  kinds  and  the  green  stubble  itself,  by 
harrowing  and  cultivating;  (3)  the  consequent  concentration  of  the  chinch-bug  hordes 
in  the  shocks;  (4)  the  heavy  rains  which  fell  about  September  16  and  17,  wetting  the 
shocks  and  thoroughly  drenching  the  chinch-bugs;  and  (5)  the  retention  of  the  chinch- 
bugs  in  the  shocks  at  a  time  when  their  food  supply  was  short,  and  when  the  moisture 
was  also  sufficient  for  the  germination  of  any  spores  of  the  white  fungus  that  may 
have  been  present. 

Mr.  Hurd  wrote  the  office,  November  20,  that  the  disease  was  still  present  in 
these  shocks,  and  that  he  had  collected  an  abundant  supply  for  use  next  spring. 

No.  77.  This  is  a  farmer's  field  contagion  experiment  made  by  Mr.  George  W. 
Heth  on  his  farm  (see  PI.  III.)  about  five  miles  west  of  Edgewood,  in  West  township, 
in  the  extreme  southwest  corner  of  Effingham  county.  It  is  the  last  of  the  three  ex- 
ceptional cases  of  the  development  of  white  muscardine  in  the  field,  to  which  refer- 
ence has  already  been  made. 

The  material  used  in  this  experiment  was  derived  from  two  original  sources;  the 
first,  a  small  number  of  chinch-bugs  dead  with  Sporotrichum  received  by  Mr.  Heth 
May  15,  from  Chancellor  Snow,  of  the  University  of  Kansas;  the  second,  similar 
material  sent  him  early  in  June  from  my  office,  from  No.  54  of  this  series.  The 
fungus-covered  specimens  received  from  Kansas  were  scattered  directly  (May  15) 
among  chinch-bugs  in  wheat  (see  A,  PI.  III.)  at  about  the  center  of  the  field.  The 
bugs  were  very  abundant  at  the  time,  practically  covering  the  wheat  everywhere 
throughout  the  field.  A  slight  rain  fell  May  17,  followed  by  heavy  storms  on  each 
succeeding  day  until  the  2oth.  The  fungus  did  not  seem  to  spread,  and  the  chinch- 
bug  attack  became  daily  more  intense.  Dry  weather  followed  until  the  middle  of 
June,  when,  according  to  Mr.  Heth's  observations,  no  traces  of  disease  could  be  found 
in  the  field.  In  the  meantime  the  second  lot  of  specimens  above  mentioned,  derived 
from  No.  54,  had  been  placed  by  Mr.  Heth  in  a  large  pasteboard  box  stocked  June  10 
in  the  usual  manner  for  infection  purposes,  but,  according  to  his  somewhat  vague 
statement,  without  very  successful  results.  Several  days  afterwards  Mr.  Heth  began 
to  distribute  this  material  in  his  wheat.  '  'I  removed  some  of  the  insects  from  the  box, " 
he  says,  "part  of  which  were  white  with  fungus,  every  second  day,  and  scattered  them 
over  the  ground  near  the  center  of  the  wheat  field  A,  where  the  bugs  were  extremely 
thick.  These  distributions  were  made  in  the  evening  and  were  kept  up  for  about  a 
week,  but  the  soil  was  very  dry."  Rains  fell  on  the  i6th  and  I7th  of  June,  but  no 
traces  of  muscardine  could  be  found  on  the  i8th,  or  at  the  time  when  the  wheat  was 
cut,  June  25.  The  ground  was,  in  fact,  in  many  places  almost  black  with  living 
chinch-bugs  at  that  time,  and  there  was  a  general  movement  to  the  north  and  east 
into  corn  fields  adjoining  (marked  B  and  C  on  PI.  III.),  the  greater  number  going, 
however,  into  field  C,  where  the  corn  was  presently  almost  completely  destroyed. 
The  destructive  horde  passed  thence  successively  into  fields  D,  E,  F,  and  G,  where 
they  continued  their  ravages  until  late  in  the  fall. 


1895.]  EXPERIMENTS    WITH    CHINCH-BUGS.  67 

On  September  28,  while  examining  the  grass  in  the  orchard  F,  at  the  point  a, 
Mr.  Johnson  discovered  many  dead  chinch-bugs  on  the  ground  under  the  stools  of 
grass  thickly  enveloped  in  a  dense,  fresh  growth  of  Sporotrichum.  Half  a  dozen 
whitened  bodies  were  taken  from  under  a  single  stool  at  this  point;  but  for  every  dead 
bug  collected,  several  hundred  live  ones  were  seen.  The  fungus-covered  insects  were 
about  equally  distributed  throughout  F  and  G,  along  a  line  north  from  a;  but  to 
the  south  of  this  point  the  dead  bugs  were  not  so  abundant,  while,  on  the  other  hand 
the  live  insects  were  just  as  numerous.  This  was  perhaps  due  to  the  fact  that  this 
was  the  highest  portion  of  the  field,  and  was  considerably  dryer  than  at  a  and 
points  further  north.  The  chinch-bugs  had  spread  over  about  three  acres,  and  had 
killed  all  the  grass  west  of  the  wavy  line  passing  through  F  and  G.  The  grass  was 
parched  and  brown  and  the  victorious  chinch-bug  hosts  were  steadily  advancing  east- 
ward. 

A  careful  examination  of  the  grass  west  of  a,  revealed  the  fact  that  the  number 
of  bugs  dead  with  the  fungus  increased  as  the  sorghum  (E)  was  approached;  that  is, 
the  number  of  fungus-covered  bugs  counted  on  a  given  area — one  square  foot — 
constantly  increased  until  the  point  b  was  reached,  at  which  place  the  greatest 
numbers  were  observed,  and  then  gradually  decreased,  practically  disappearing  at  c, 
as  we  passed  into  the  corn  (D).  At  l>  two  hundred  and  seventy-one  whitened  bodies 
were  counted  on  the  surface  of  the  ground  scattered  over  a  single  square  foot.  The 
ground  at  this  point,  however,  was  thickly  strewn  with  sorghum  leaves  and  was  quite 
damp. 

Another  interesting  point  observed  at  this  time  was  the  comparative  age  of  the 
fungus  along  a  line  from  a  to  c.  At  a,  as  already  indicated,  the  fungous  growth  was 
fresh,  and  in  some  instances  the  mycelial  threads  were  but  just  starting,  being  but 
barely  visible  on  the  bodies  of  the  dead  bugs.  As  we  approached  b,  however,  it 
became  evident  that  the  fungus  on  the  insects  was  of  a  much  older  growth.  At  a  point 
midway  between  a  and  b,  bugs  dead  with  the  fungous  disease  were  found,  from  which 
the  spores  were  not  easily  detached;  while  at  b  the  spores  were  easily  shaken  off,  and 
in  most  cases  the  ground  where  a  dead  bug  had  been  lying  was  so  dusted  with  them 
as  to  present  a  whitish,  mouldy  appearance.  From  b  to  c  the  fungus  was  of  a  still 
earlier  growth.  Along  a  dead  furrow  at  the  latter  point,  several  dirty  whitish, 
mouldy  spots  on  the  surface  of  the  ground  under  a  fallen  corn  leaf  or  stalk,  or  other 
rubbish,  was  all  the  evidence  that  could  be  found  that  the  fungus  had  been  present. 

Comparatively  few  chinch-bugs  dead  with  the  white  fungus  were  found  in  corn 
B,  C,  H,  I,  and  J,  not  more  than  half  a  dozen  being  taken  from  each  field.  Their 
whitened  bodies  were  perhaps  more  abundant  in  corn  H  along  the  south  side  in  the 
immediate  vicinity  of  the  meadow  G,  than  in  any  of  the  other  fields  examined.  Live 
chinch-bugs,  mostly  pupae  and  adults,  were  quite  numerous  throughout  all  these 
fields.  All  the  meadows  adjoining  corn  on  this  farm  were  more  or  less  injured  from 
the  attacks  of  the  chinch  bug,  but  little  or  no  fungus  was  found  in  any  of  them  except 
those  already  mentioned,  F  and  G.  Only  an  occasional  live  insect  was  seen  in  the 
wheat  stubble  A,  in  which  the  infection  had  been  placed,  and  in  the  stubble  of  oats 
and  wheat  south  and  east  of  the  house. 

A  dozen  or  more  insects  dead  with  Sporotrichum  were  found  in  a  corn  field 
belonging  to  Mr.  Wm.  Kelley  one  mile  east  of  the  Heth  farm,  and  several  were  taken 
from  the  surface  of  the  ground  under  stools  of  foxtail-grass  along  the  roadside  in  the 
immediate  vicinity  of  the  same  field. 

The  Heth  farm  as  well  as  the  surrounding  country  was  again  examined  by 
Mr.  Johnson  and  myself  October  10.  The  fungous  attack  had  not  increased  in  inten- 
sity, so  far  as  could  be  ascertained,  in  the  meadows  F  and  G;  but  the  chinch-bugs 
had  continued  their  ravages,  and  the  irregular  line  marking  the  boundary  between  the 
infested  area  and  the  remainder  of  F  and  G  had  moved  several  feet  eastward.  The 
whitened  bodies  of  dead  bugs  could  be  easily  found  on  the  ground  by  parting  the 


68  BULLETIN  NO.  38.  [March, 

grass  at  any  place  west  of  the  division  line,  and  they  were  quite  abundant  under 
leaves  and  rubbish  in  the  sorghum  stubble  E,  but  the  growth  in  this  latter  place  had 
the  characteristic  weathered  appearance  of  over-ripeness.  In  corn  D  an  occasional 
trace  of  the  fungus  could  be  seen,  and  several  chinch-bugs  imbedded  in  it  were  found 
under  stools  of  grass  along  the  roadside  between  C  and  D.  In  corn  B  the  fungus 
was  found  in  shocks  and  in  the  open  field  in  the  stubble,  but  that  from  the  surface  of 
the  ground  under  the  shocks  was  of  a  much  more  recent  growth  than  that  taken  from 
the  open  field.  An  occasional  bug  dead  with  this  disease  occurred  on  the  ground  in 
the  uncut  corn  in  the][same  field. 

One  mile  east, [on  the  Kelley  farm,  to  which  reference  has  been  made,  chinch- 
bugs  enveloped  in  the  white  fungus  were  found  in  corn  on  the  ground  in  low,  damp 
places,  under  fallen  leaves,  weeds,  grasses,  and  other  rubbish.  They  were  also  quite 
abundant  along  the  roadside  under  stools  of  grass,  but  on  the  whole  the  fungus  was 
not  so  plentiful  as  twelve  days  previous,  and  the  growth  was  comparatively  old.  In 
an  adjoining  wheat  field,  a  considerable  number  of  dead  insects  were  found  attached 
to  the  blades  of  young  wheat  plants,  and  on  the  ground  between  the  drill  rows.  After 
counting  both  live  and  dead  chinch-bugs  on  a  given  area,  it  was  estimated  that  about 
twenty-eight  per  cent,  were  dead.  Subsequent  examination  of  collected  specimens 
showed,  however,  that  the  destructive  agent  in  this  instance  was  the  gray  muscardine 
(Entomophthora  aphidis};  but  a  few  dead  chinch-bugs  from  this  field,  showing  no 
external  trace  of  a  fungous  growth,  developed  a  profuse  growth  of  the  white  muscar- 
dine when  placed  on  damp  sand.  This  fungus  was  also  found  on  chinch-bugs  in  all 
corn  fields  examined  at  this  time  for  a  distance  of  four  miles  south  of  the  Heth  farm, 
but  was  nowhere  as  abundant  as  on  the  latter  place. 

It  has  been  already  reported  on  page  53  that  the  white  fungus  of  the  chinch-bug 
was  very  widely  distributed  throughout  adjoining  counties  at  this  date,  and  the  gen- 
eral tenor  of  our  observations  at  this  time  supports  the  hypothesis  that  the  Heth  out- 
break was  a  spontaneous  one,  arising  under  the  influence  of  especially  favorable 
conditions,  which  were  substantially  as  follows:  (i)  an  abundance  of  food — wheat, 
corn,  sorghum,  and  grass,  into  which  the  chinch-bug  hosts  passed  successively  after 
each  harvest,  thus  keeping  them  somewhat  concentrated;  (2)  the  appearance  of  the 
fungous  disease  on  chinch-bugs  along  a  dead  furrow  running  north  and  south  through 
c,  at  a  time  when  the  destruction  to  corn  was  about  complete,  and  when  myriads  of 
insects  were  passing  this  point,  going  into  sorghum,  E;  (3)  the  concentration  of  the 
bugs  on  this  narrow  strip  of  sorghum — practically  accumulating  the  chinch-bugs  of 
thirty-five  acres  on  these  nine  rows;  (4)  the  stripping  and  cutting  of  this  sorghum  at 
a  time  when  the  insects  were  most  numerous,  which  knocked  them  to  the  ground  in 
great  masses,  where  they  remained  under  and  among  the  leaves  for  several  days;  (5) 
the  occurrence  of  a  heavy  rain  September  12,  followed  by  a  high  temperature,  and 
another  heavy  rain  September  16;  and  (6)  the  close  proximity  of  the  meadows  F  and 
G,  into  which  the  bugs  passed,  and  where  they  remained  on  the  damp  ground  under 
the  grass. 

It  thus  seems  quite  probable  that  this  fungous  outbreak  had  little  or  no  connection 
with  the  infection  material  distributed  during  the  early  part  of  the  season,  but  that  it 
was  simply  a  local  development,  under  exceptionally  favorable  conditions,  of  the 
diffuse  general  spread  of  chinch-bug  disease  throughout  this  whole  country  at  this 
time. 

The  three  following  (Nos.  78-80)  are  successive  farmers'  experi- 
ments conducted  in  the  counties  of  Cumberland,  Bond,  and  Clay.  Indi- 
vidual reports  on  these  farmers'  experiments  were  not  called  for,  and 
the  report  here  given  for  78  and  79  is  based  upon  a  single  visit  made 
by  Mr.  Johnson  early  in  October.  No.  80  was  visited  twice. 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  69 

No.  78.  A  farmer's  experiment,  the  original  material  for  which  was  derived 
from  our  experiment  No.  54.  It  was  sent  from  this  office  June  25  to  Mr.  Thomas 
B.  Wilson,  Sr.,  Greenup,  Cumberland  county,  and  used  by  him  to  start  a  con- 
tagion box,  according  to  our  circular  of  directions  (see  p.  28).  This  box  was  kept  in 
operation  until  late  in  July,  live  bugs  and  fresh  food  being  introduced  every  other 
day,  and  the  fungus-covered  insects  removed  each  time  the  box  was  opened.  Several 
hundred  such  specimens  were  distributed  during  the  first  two  weeks  of  July  at  the 
bases  of  the  stalks  and  behind  the  leaves  of  corn  along  one  side  of  a  field  adjoining 
wheat,  in  places  where  the  chinch-bugs  were  most  abundant.  The  ground  was  very 
dry,  and  the  experiment  was  a  failure,  no  trace  of  the  fungus  appearing  so  far  as 
could  be  ascertained  by  weekly  examinations  kept  up  until  late  in  September.  These 
fields  were  examined  by  Mr.  Johnson  October  9,  but  no  trace  of  insect  disease 
could  then  be  found,  although  adults  and  pupae  of  the  chinch-bug  were  still  abundant 
in  the  corn.  The  first  fifteen  rows  adjoining  the  wheat  had  been  completely  de- 
stroyed, only  here  and  there  a  stalk  still  standing  erect.  On  this  same  visit  several 
bugs  imbedded  in  Sporotrichum  were  taken  from  corn  shocks  about  two  miles  from 
town,  in  another  direction. 

No.  79.  A  farmer's  experiment,  conducted  by  Mr.  W.  E.  Jackson,  of  Greenville, 
Bond  county,  with  material  from  No.  54.  About  a  dozen  chinch-bugs,  received  from  this 
office,  were  placed  in  a  box  July  i,  prepared  according  to  our  directions,  with  live  insects 
and  fresh  food,  both  of  which  were  renewed  as  necessary,  a  few  whitened  bugs  being 
taken  out  of  the  box  each  time  that  it  was  opened,  and  distributed  in  the  corn.  July 
15  about  a  hundred  fungus-covered  specimens  were  placed  behind  leaves  and  on  the 
ground,  where  the  bugs  were  most  abundant,  in  a  field  of  corn  on  Mr.  A.  H.  Jackson's 
farm,  a  quarter  of  a  mile  south  of  his  house.  Two  similar  distributions  were  made 
in  this  field  July  28  and  August  12.  The  corn  was  examined  every  week,  but  no  indi- 
cation was  found  that  the  disease  was  spreading,  the  chinch-bug  attack,  in  fact, 
increasing  steadily  week  by  week.  The  corn  was  cut  and  shocked  about  September  3, 
in  order  to  save  it  for  fodder,  and  the  bugs  collected  in  the  shocks,  where  they  remained 
until  late  in  fall.  This  field  was  carefully  examined  by  Mr.  Johnson  October  10. 
The  corn  had  been  thoroughly  wet  by  heavy  rains  soon  after  cutting,  and  the  ground 
was  still  very  wet  under  the  shocks.  There  was  little  or  no  grass  in  the  open  field, 
and  consequently  very  few  chinch-bugs.  They  were  quite  abundant  in  the  shocks, 
and  numerous  in  an  adjoining  meadow,  but  not  sufficiently  so  to  do  any  appre- 
ciable damage.  A  careful  search  was  made  in  shocks  all  over  the  field,  but  no 
traces  of  the  white  fungus  were  found,  except  in  four  shocks  in  the  northeast  corner, 
and  here  the  greater  part  of  the  diseased  insects  were  found  in  the  third  shock  of  the 
first  row  on  the  north,  counting  from  the  east.  Several  hundred  chinch-bugs  and 
three  beetles  (Coccinella  g-notata  Hbst.,  Ataenius  stercorator,  Fab.,  and  Epicauta  vittata, 
Fab.)  completely  enveloped  in  the  white  fungus  were  taken  from  the  ground  and 
from  behind  leaves  in  this  shock.  Half  a  dozen  chinch-bugs  dead  with  Sporotrichum 
were  taken  from  three  other  shocks  in  the  immediate  vicinity.  The  disease  was  also 
found  in  small  quantities  in  corn  shocks  directly  east  on  the  opposite  side  of  the  road; 
and  three  whitened  bodies  were  taken  from  a  low  damp  furrow  or  ditch  in  the 
meadow  adjoining  on  the  north.  A  few  fungus-covered  bugs  were  found  in  corn 
shocks  in  an  orchard  near  the  house,  and  quite  a  number  were  found  in  shocks  and 
on  the  ground  in  low  damp  places  in  a  corn  field  one  mile  east. 

Just  why  the  disease  should  have  been  so  abundant  in  the  single  shock  men- 
tioned above,  and  totally  absent  or  nearly  so  in  all  other  shocks  in  the  field,  we  will 
not  attempt  to  explain.  Suffice  it  to  say  that  the  infection  was  distributed  along  this 
side  of  the  field,  and  that  all  the  other  shocks  in  the  same  row  were  similarly  situated 
and  cut  at  the  same  time. 

The  experiment  was  a  failure,  and  did  not  arrest  the  ravages  of  the  bugs  in  the 
least.  A  part  of  the  fungus-covered  bugs  collected  in  these  fields  were  placed  in 
W.  E.  Jackson's  hands  for  future  experimental  purposes. 


70  RL-LI.ETIX   NO.   38.  [March, 

No.  80.  A  farmer's  experiment,  made  by  Mr.  C.  M.  Filson,  Xenia,  Clay  county, 
the  original  material  for  which  was  derived  from  this  office.  The  box  was  carefully 
prepared  according  to  our  circular  of  directions  (see  p.  28),  and  infected  June  20  with 
about  a  dozen  bugs  from  No.  54,  this  series.  The  box  was  kept  on  the  damp  floor  of 
a  cidar  house.  Bugs  enveloped  in  the  white  fungus  were  removed  every  fourth  or 
fifth  day,  and  live  insects  and  fresh  food  were  added  as  required  This  box  was  kept 
in  active  use  until  about  September  i.  It  was  examined  by  Mr.  Johnson  September 
27,  at  which  time,  although  the  insects  were  all  dead  and  the  food  was  dried  up,  it 
was  still  in  good  condition,  and  about  a  hundred  chinch-bugs,  thickly  imbedded  in  the 
muscardine  fungus,  were  taken  out  and  given  to  Mr.  Filson  for  future  use.  Several 
hundred  fungus-covered  bugs  from  this  box  were  distributed  in  corn  along  the  north 
and  south  sides  of  a  field  on  Mr.  Filson's  farm  about  July  i,  and  about  ten  other  dis- 
tributions were  made  at  regular  intervals  after  a  rain  or  on  damp  mornings,  with 
bugs  from  the  same  source.  Chinch-bugs  entered  this  corn  from  an  adjoining  wheat 
field,  literally  covering  the  stalks  in  many  places.  This  field  was  examined  about 
every  third  day,  but  no  trace  whatever  of  the  white  fungus  was  detected.  As  a  con- 
sequence, this  experiment  was  abandoned,  and  other  measures  were  taken  by  the 
owner  to  arrest  the  ravages  of  the  chinch-bug  (see  No.  89).  Mr.  Johnson  examined 
this  field  September  27  and  again  October  6,  but  did  not  find  a  single  infected  insect. 
The  corn  had  been  cut  at  the  time  first  mentioned,  but  the  bugs  were  still  quite 
abundant  in  the  shocks,  and  foxtail  and  other  grasses  along  the  fences  and  in  low 
damp  spots  throughout  the  field  were  thickly  covered  by  them. 

Several  fungus-covered  bugs  were  found  by  Mr.  Johnson  September  27  in  grass 
along  the  roadside  more  than  a  mile  from  Mr.  Filson's  farm;  and  again  on  the  Filson 
farm  also  during  the  latter  part  of  November.  December  10  Mr.  Filson  writes: 
"  I  could  see  no  effect  of  the  disease  on  my  farm  until  after  the  recent  rain.  At  the 
present  time  I  find  chinch-bugs  covered  with  fungus  in  all  the  shocks  in  corn  adjoin- 
ing timber." 

2.     EXPERIMENTS   WITH   BARRIERS   AND   TRAPS. 

The  six  following  (Nos.  81-86)  are  field  experiments  with  barriers 
and  traps  conducted  by  us  this  summer  on  the  University  farm.  The 
appearance  of  the  chinch-bug  here,  for  the  first  time  since  1883  in  num- 
bers sufficient  to  do  noticeable  injury,  gave  us  an  especially  favorable 
opportunity  for  careful  experimental  work.  Experiments  Si,  82,  and  83 
were  made  on  a  small  scale  to  test  the  efficiency  of  the  furrow  and  post- 
hole  method  for  the  arrest  and  destruction  of  chinch-bugs  while  escaping 
from  fields  of  small  grain  at  harvest  time.  Numbers  84  and  85  were 
made  to  test  the  value  of  the  coal-tar  barrier,  and  86  was  a  practical  test 
of  the  two  combined. 

No.  81.  This  is  a  furrow  experiment  made  July  10.  A  patch  of  wheat  stubble 
ground  (B,  Plate  II.,  in  the  vicinity  of  c),  4x6  feet,  was  cleared  off  with  a  spade  so 
that  the  surface  was  hard  and  smooth.  Around  this  we  dug  up  and  pulverized  a 
narrow  strip  of  ground,  in  which  a  dusty  furrow  was  made  three  inches  deep  inside 
and  six  inches  outside,  enclosing  the  entire  patch.  The  outer  face  of  this  furrow  had 
a  slope  varying  from  50°  to  60°. 

At  2:10  P.  M.  we  released  in  this  enclosure  over  a  pint  of  chinch-bugs*  collected 
from  corn  adjacent,  and  observed  their  operations  in  the  ditch.  Probably  one-fourth 
of  those  collected  were  adults,  the  remainder  being  of  various  ages — mostly  pupae,  or 

*The  numbers  of  chinch-bugs  used  in  these  experiments  were  determined  by  counting  those  in 
a  given  measure,  10  c.  c.;  a  pint  being  thus  ascertained  to  contain  about  132,500;  a  quart  265,000;  and 
.a  bushel  8,480,000. 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  Jl 

in  the  stage  immediately  preceding.  The  adults  were  much  the  more  active,  the 
immature  forms  tending  to  accumulate  and  pile  up  on  each  other  in  the  ditch. 

The  greater  part  of  the  chinch-bugs  presently  deserted  the  interior  of  the 
enclosure  and  attempted  to  escape  from  the  ditch,  forming  a  continuous  belt  in  the 
bottom  one  to  three  inches  wide  and,  where  thickest,  two  or  three  layers  deep.  In 
their  efforts  to  escape,  the  adult  bugs  persistently  climbed  up  the  outer  face  of  the 
furrow  again  and  again,  without  cessation,  falling  back  each  time  to  the  bottom  as 
the  dust  gave  way  beneath  them,  the  result  being  finally  to  accumulate  a  slope  or 
talus  of  dirt  at  the  bottom  of  the  furrow  of  an  incline  sufficiently  gradual  to  permit 
them  to  climb  it  easily.  In  this  manner  they  slowly  advanced  upward,  until  in  an 
hour  and  a  half  from  the  beginning  of  the  experiment  a  few  escaped  at  one  corner  by 
climbing  up  a  kind  of  ladder-way  of  small  clods  and  roots  projecting  from  the  sur- 
face. Not  over  fifteen  or  twenty  thus  released  themselves,  when  the  clods  were 
undermined  and  fell,  breaking  the  passageway. 

An  hour  and  three-quarters  from  the  beginning,  a  post-hole  was  made  in  the 
furrow  at  one  end  of  the  enclosure.  The  chinch-bugs  nearest  it  presently  fell  in,  and 
as  others  advanced  to  take  their  places — apparently  impelled  by  the  pressure  from 
their  neighbors — they  were  also  trapped.  The  impulse  was  thus  gradually  passed 
along  the  struggling  line  until  within  a  few  minutes  there  was  a  definite  movement  of 
the  entire  body  of  chinch-bugs  for  about  three  feet  on  each  side  of  the  hole  towards 
and  into  it.  By  4  o'clock,  probably  half  of  the  chinch-bugs  in  the  enclosure  had 
been  trapped.  This  movement  had  so  greatly  diminished  the  progress  of  those 
attempting  to  ascend  the  side  of  the  furrow,  that  at  this  time  they  had  nowhere  gen- 
erally advanced  beyond  an  inch  below  the  upper  edge.  Without  the  post-hole  it  is 
likely  that  they  would  have  begun  to  make  their  escape  in  considerable  numbers  in 
about  two  hours  from  the  time  the  experiment  began. 

We  collected  and  brought  to  the  laboratory  from  the  post-hole  trap  and  from  the 
furrows  about  one  pint  of  chinch  bugs,  leaving  the  remainder  in  the  enclosure.  Next 
morning  the  greater  part  of  these — probably  all  except  the  adults — were  dead  in  the 
bottom  of  the  furrow,  killed  by  exposure  to  the  sun 

No.  82.  July  ii,  two  parallel  furrows  twenty-five  feet  long  were  made  in  a 
thoroughly  pulverized  strip  of  ground,  in  wheat  stubble  (B,  Plate  II.),  by  dragging 
an  eight-inch  log  back  and  forth  through  the  dirt.  These  furrows  were  connected  at 
their  ends  by  transverse  furrows  of  the  same  character,  thus  enclosing  a  strip  of 
solid,  smooth  ground  between  them  a  foot  and  a  half  across.  The  furrows  were  two 
inches  deep  inside  and  five  inches  outside,  the  outer  slopes  varying  from  40°  to  54°  30'. 

Collected  a  quart  and  a  gill  of  chinch-bugs  (estimated  number  300,000)  from 
adjacent  corn,  C,  and  placed  them  on  the  strip  enclosed  by  the  furrows,  distributing 
them  the  whole  length  of  the  plat.  A  few  adults  flew  at  once,  and  several  others 
made  the  attempt,  as,  indeed,  adults  had  occasionally  done  the  day  before.  In  twenty 
minutes  probably  nine-tenths  of  them  were  dead  upon  the  ground,  evidently  from  the 
heat  of  the  sun.  Most  of  them  had  died  on  the  hard  earth  between  the  furrows 
without  reaching  the  latter.  Two-thirds  of  those  in  the  furrows  at  this  time  were 
adults  Those  dead  from  the  heat  were  nearly  all  young,  but  an  occasional  adult  was 
seen  among  them. 

The  principal  movement  of  the  imprisoned  chinch-bugs  was  at  first  to  the  north, 
in  the  furrow  on  that  side,  but  presently  they  abandoned  their  attempt  to  scale  this 
slope,  and  all  remaining  alive  resorted  to  the  south  furrow,  collecting  chiefly  at  two 
points.  This  was  evidently  due  to  the  greater  heat  of  the  north  furrow  on  account  of 
its  more  direct  exposure  to  the  sun.  As  the  chinch-bugs  work  at  a  somewhat  steep 
slope  they  gradually  undermine  it,  leaving  an  overhanging  ledge  which  they  cannot 
scale,  but  which  they  gradually  work  down  in  their  efforts  to  climb  the  bank. 

The  temperature  of  the  earth  determined  by  simply  laying  a  thermometer  on  it 
in  the  sun,  was  116°  Fah.  at  11:05.  If  tne  thermometer  were  barely  buried  in  the 


72  BULLETIN    NO.    38 

dust  it  was  122°.    The  air  tempsrature  at  the  same  time- was  91°.     Sky  cloudless,  and 
a  gentle  wind. 

To  verify  the  effect  of  the  hot  earth  and  sun  upon  chinch-bugs,  an  additional  pint 
was  collected  and  put  into  the  small  enclosure  used  the  preceding  day.  These  were 
killed  as  above,  and  almost  as  rapidly.  Wherever  a  rootlet,  or  any  other  solid 
substance,  projected  above  the  surface,  it  was  thickly  covered  with  chinch-bugs,  and 
a  stick  of  any  kind  thrust  in  among  them  would  be  immediately  blackened  by  them, 
as  they  crawled  upward,  collecting  at  the  top,  and  dropping  off  as  they  crowded  each 
other  outward.  Taking  advantage  of  this  fact,  a  small  trap  was  arranged  by  inclining 
sticks  over  a  dipper  of  coal-tar.  Two  or  three  fluid  ounces  of  chinch-bugs  were  col- 
lected in  this  way  in  the  course  of  half  an  hour.  This  is,  however,  a  very  much  less 
rapid  method  than  the  post-hole  trap. 

We  estimated  that  at  the  rate  of  action  of  the  chinch-bugs  in  these  furrows  a 
single  man  could  certainly  supervise  eighty  rods  along  the  edge  of  a  field,  and  prob- 
ably twice  as  great  a  distance. 

No.  83.  July  12  a  quantity  of  chinch-bugs  was  placed  in  the  large  enclosure 
described  under  experiment  82,  the  first  at  6:25  A.  M.  and  a  second  lot  at  7,  and  a 
coffee  can  was  sunk  in  the  furrow  at  one  end  of  the  plat. 

At  7:40  chinch-bugs  placed  in  the  southern  furrow  and  a  belt  of  coal-tar  poured 
along  the  middle  of  the  enclosed  space.  Day  clear  and  rather  windy.  At  one  place 
where  the  slope  was  58°,  chinch-bugs  began  to  escape  almost  at  once;  but  by  steep- 
ening, the  furrow  at  this  point  with  a  hoe,  we  confined  them  permanently,  only  a  very 
few  escaping  by  making  here  and  there  a  temporary  passageway  which  permitted 
now  and  then  one,  at  long  intervals,  to  emerge.  Such  passageways  were  presently 
undermined,  and  the  number  escaping  was  entirely  insignificant. 

Chinch-bugs  began  to  collect  in  the  can  as  soon  as  they  were  placed  in  the  fur- 
row, but  the  angle  of  the  furrow  near  it  arresting  them,  a  second  one  was  placed  in 
the  middle  of  the  furrow.  Into  this  can  they  fell  in  quantity,  presently  marching 
towards  it  from  the  right  and  left,  thinning  out  the  crowd  in  the  furrow  for  a 
distance  of  nine  feet  on  one  side  and  ten  to  twelve  feet  on  the  other,  until  by  9  o'clock 
the  attack  was  practically  broken  all  along  the  line  by  the  capture  of  nearly  all  of  the 
bugs. 

At  6:45  the  temperature  of  the  ground — the  thermometer  being  lightly  covered 
with  dust — was  79°;  that  of  the  air,  in  the  sun,  82°. 

At  8:15  the  temperature  of  the  dirt,  taken  as  above,  was  97°,  and  that  of  the  air, 
85° — thermometer  erect  in  the  sun. 

At  9,  chinch-bugs  had  begun  to  die  where  most  exposed  to  sun.  Dirt  was  here 
108°;  air  87^  °,  with  thermometer  erect. 

No.  84.  July  12,  a  patch  of  wheat  stubble  was  cleared  off,  as  in  experiment  81, 
and  at  7:30  P.  M.  a  belt  of  coal-tar  two  inches  wide  was  put  down,  forming  an  oval, 
enclosing  a  space  twenty-five  feet  long  by  two  feet  across.  Post-holes  about  ten  inches 
deep  were  dug  at  either  end,  with  a  common  post-hole  digger.  Coffee  cans,  about 
six  inches  in  diameter  and  seven  or  eight  inches  in  depth,  were  placed  in  the' post 
holes  so  that  the  entrapped  chinch-bugs  could  be  easily  removed  and  measured. 

At  7:45  P.  M.  half  a  pint  of  chinch-bugs  was  distributed  over  the  hard,  smooth 
surface  within  the  enclosure.  At  first  they  went  in  all  directions,  and  many  ran  head- 
long into  the  tar  and  were  destroyed;  but  the  greater  number  were  more  deliberate, 
and  moved  up  and  down  the  tar  line  without  making  any  attempt  to  cross  it.  By 
7:50  a  large  proportion  had  passed  from  the  middle  of  the  enclosure  to  the  edge  of  the 
tar,  principally  on  the  south  side,  but  forming  a  belt,  as  it  were,  around  the  entire 
enclosure,  the  general  movement  being  eastward. 

At  8  o'clock  they  were  less  active  and  were  most  abundant  at  the  ends  of  the  oval, 
but  very  few  had  fallen  into  the  post-holes.  There  was  no  disposition  to  climb  root- 
lets or  other  projections  above'the  surface. 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  73 

At  8:30  they  were  still  less  active,  and  were  collecting  together  in  masses  on  small 
lumps  of  earth  and  in  depressions  on  the  surface.  No  general  movement  observed  at 
this  time.  About  fifteen  hundred  chinch-bugs  were  removed  from  each  can.  They 
were  most  abundant  in  the  east  and  west  ends  and  along  the  south  side  of  the  oval. 
The  slightest  disturbance,  such  as  the  movement  of  a  finger  on  the  ground  in  their 
midst,  caused  the  greatest  confusion  among  them. 

The  sky  was  clear  with  a  gentle  breeze  from  the  west.  Temperature  of  air  at 
7:30  was  82°,  the  thermometer  held  erect;  surface  82°,  as  determined  by  simply 
laying  the  thermometer  on  the  ground. 

At  8:30  both  air  and  surface  were  74°,  observations  being  taken  as  above. 

At  5  A.  M.,  July  13,  the  young  were  more  active  than  the  adults,  and  a  great 
many  bugs  were  still  collected  on  lumps  of  earth  and  in  depressions  on  the  surface. 
A  few  were  crawling  and  falling  into  the  post-holes,  about  as  many  having  been 
trapped  in  eight  hours  and  a  half  during  the  night  as  had  been  caught  the  previous 
evening  in  three-quarters  of  an  hour. 

At  6  o'clock  the  temperature  of  the  air  was  74°,  thermometer  erect  and  about  four 
feet  above  the  surface.  The  soil  temperature  was  78°,  thermometer  slightly  buried. 
The  chinch-bugs  were  now  very  much  more  active  and  were  moving  in  considerable 
numbers  toward  the  east  end  of  the  oval,  about  six  times  as  many  (9  ooo  in  round 
numbers)  having  collected  in  the  post-hole  at  this  point  since  5  o'clock  as  had  been 
entrapped  during  the  entire  night.  Their  activity  steadily  increased,  and  in  a  few 
moments  there  was  a  regular  procession  fourteen  feet  long  moving  to  the  eastward 
along  the  tar  line  towards  one  end  of  the  oval,  and  to  the  westward  for  a  distance  of 
six  feet  towards  the  other,  leaving  an  intermediate  space  of  about  five  feet  where 
there  was  no  appreciable  tendency  in  either  direction  Very  few  bugs  passed  the  tar 
line,  although  it  was  dry  and  could  easily  have  been  crossed.  It  served,  practically, 
as  an  impassable  barrier. 

At  9  A.  M.  the  temperature  of  the  air  was  85°;  surface  112°.  The  oval  was 
almost  entirely  freed  from  chinch-bugs,  the  most  of  them  having  fallen  into  the  post- 
holes.  Two-thirds  of  the  entire  lot  that  had  been  placed  in  this  enclosure  the  pre- 
vious evening,  were  taken  from  the  cans,  the  great  majority  having  fallen  in  since  6 
A.  M.  If  the  three  thousand  chinch-bugs  taken  from  the  post-holes  at  8:30  P.  M.  the 
preceding  day  and  those  still  remaining  within  the  oval  are  taken  into  consideration, 
it  is  clear  that  only  a  very  small  number  escaped. 

No.  85.  July  13,  an  experiment  similar  to  No.  84  was  made  on  an  oval  half  as 
large,  with  post-hole  in  one  end.  Slight  rain  at  2  p.  M.,  just  enough  to  settle  the  dust. 
Sky  cloudy,  with  light  breeze  from  southwest;  temperature  of  air  90°;  surface  87°. 

At  2:30  P.  M.  renewed  barrier  by  pouring  coal-tar  over  line  used  the  day  before, 
for  a  distance  of  twelve  feet  on  either  side,  and  across  the  ends;  but  at  the  east  end 
the  tar  was  poured  over  the  ground,  as  no  line  had  been  previously  made  at  this  point. 
One  gill  of  chinch-bugs  was  distributed  on  the  surface  of  the  hard  ground  enclosed. 
They  were  very  active,  and  in  fen  minutes  the  center  of  the  oval  was  comparatively 
free,  the  insects  forming  a  band  next  the  tar  line  around  the  entire  enclosure.  By  3 
p.  M.  the  bugs  had  mostly  collected  on  the  south  side  and  in  the  ends,  being  most 
abundant  in  the  east  end,  where  they  were  very  active.  The  general  movement  at 
this  time  was  to  the  eastward,  but  many  were  tumbling  into  the  can  at  the  west  end  . 
A  strong  wind  from  the  southwest  blew  many  insects  over  the  line. 

Outside  the  tar  line  myriads  of  young  bugs  just  from  the  egg  were  moving 
southward  in  the  direction  of  the  adjoining  corn  C  (PI.  II.),  literally  covering  the 
ground  in  many  places.  Not  a  single  insect  attempted  to  cross  the  tar,  although  in 
heir  confusion  they  scrambled  about  in  all  other  directions;  but  where  no  barrier 
intervened  they  passed  rapidly  along  towards  the  corn. 

Two-thirds  of  the  bugs  within  the  oval  had  collected  at  either  end  by  3:30  P.  M., 
and  about  two  thousand  had  fallen  into  the  can. 


74  BULLETIN   NO.    38.  [March, 

At  4:30  P.  M.  the  barrier  was  in  good  condition  except  at  one  place  where  the  coal- 
tar  had  been  poured  over  the  loose  ground  and  was  now  getting  quite  dry.  A  few  insects 
attempted  to  cross  the  line,  but  either  retreated  or  went  pell-mell  into  it  and  were 
destroyed.  One-third  of  the  entire  lot  had  collected  in  the  east  end,  and  the  others 
were  scattered  about  the  oval.  About  five  thousand  were  taken  from  the  can  and  the 
experiment  was  left  over  night. 

July  14,  at  9:30  A.  M.,  of  the  twenty-one  thousand  bugs  left  in  the  oval  the  pre 
vious  night,  less  than  two  thousand  remained,  one-half  of  these  being  in  the  can.  The 
remainder  had  escaped  during  the  night  and  early  morning  through  a  passageway 
at  the  east  end,  where  the  tar  had  become  dry  and  where  the  wind  had  blown  fine 
particles  of  dirt  over  the  surface,  completely  covering  it. 

At  10  A.  M.,  sky  clear 'and  a  gentle  westerly  breeze.  Temperature  of  air  84°; 
surface  106°;  soil  117°. 

No.  86.  July  10,  a  strip  of  ground  between  the  spring  wheat  B  and  corn  C 
(Plate  II.),  three  feet  wide,  was  thoroughly  and  deeply  pulverized  by  means  of  a  har- 
row-toothed cultivator  drawn  by  one  horse  and  a  twelve-foot  plank  drawn  endwise, 
the  driver  riding  the  harrow  or  plank  when  necessary.  Next,  a  log  about  six  feet  long 
and  eight  inches  through  was  dragged  endwise  back  and  forth  in  this  strip,  the  driver 
riding  it,  until  a  deep  furrow  had  been  made.  The  sides  of  the  furrow  were  then 
dressed  up  here  and  there  with  a  hoe. 

Similar  furrows  were  made  in  the  fifth  and  sixth  rows,  and  a  narrow  line  of  coal- 
tar  was  poured  along  the  bottom  of  the  furrow  in  the  latter  row,  from  an  ordinary 
two-gallon  sprinkler  without  the  nozzle.  On  the  first  application  one  gallon  of  tar 
was  sufficient  for  a  line  ten  rods  long,  and  thereafter  for  about  twenty  rods.  The  tar 
very  soon  formed  a  crust,  but  remained  in  good  condition  and  completely  checked  the 
advance  of  the  chinch-bugs  for  twenty-four  hours  or  longer. 

Holes  about  a  foot  deep  were  made  in  each  furrow  with  an  ordinary  post-hole 
digger  at  intervals  varying  from  ten  to  twenty  feet,  according  to  the  abundance  of  the 
bugs. 

A  strip  of  winter  wheat  (A)  of  about  four  and  a  half  acres,  badly  infested  with 
chinch-bugs,  was  cut  June  27  to  July  3.  The  bugs  then  attacked  the  narrow  strip  of 
spring  wheat  (B) — about  one  rod  wide,  running  theentire  length  ofthe  field, — which 
they  completely  ruined.  This  was  cut  July  7  and  burned  over  the  following  day. 
Many  bugs  were  destroyed,  but  the  great  majority  of  them  moved  into  the  corn  C, 
blackening  the  stalks  in  the  first  two  or  three  rows. 

The  furrow  beside  the  first  row  did  not  check  their  advance  to  a  very  great 
degree,  from  the  fact  that  it  had  been  defaced  and  broken  down  to  some  extent,  and 
was  strewn  with  straw  and  other  rubbish  from  the  wheat.  The  furrow  beside  the 
fifth  row  and  tar  line  by  the  sixth,  however,  completely  arrested  their  advance,  and 
practically  kept  them  confined  to  the  first  five  rows  A  quart  or  more  could  have 
been  easily  collected  in  a  few  minutes  by  jarring  the  stalks  and  catching  the  bugs  in 
a  pan. 

The  insects  worked  away  in  the  furrow,  endeavoring  to  escape  in  much  the  same 
manner  as  described  under  experiments  81  and  82.  An  occasional  one  made  good  its 
escape  by  means  of  a  projecting  rootlet,  or  the  rubbish  strewn  about,  but  was 
repelled  by  the  tar  line  in  the  next  row,  which  seemed  to  be  regarded  as  an  impassable 
obstacle.  In  both  cases  there  was  a  general  movement  up  and  down  the  lines,  and  the 
bugs  were  constantly  falling  into  the  post-holes,  a  pint  or  more  being  entrapped  in 
each,  where  they  were  killed  with  a  strong  mixture  of  kerosene  and  water  or  by  a 
little  coal-tar  poured  upon  them. 

In  the  furrows,  where  the  bugs  were  directly  exposed  to  the  sun,  a  great  many 
were  killed  by  the  extreme  heat,  the  tender  larvae  succumbing  first,  but  even  adults 
dying  finally. 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  75 

These  furrows  were  dressed  up  here  and  there  from  day  to  day  with  a  hoe,  as 
was  necessary,  and  the  tar  line  was  renewed  about  every  twenty-four  hours.  A  slight 
rain  fell  July  13,  just  enough  to  lay  the  dust,  and  the  furrow  in  the  fifth  row  no 
longer  restrained  the  marching  horde.  The  ground  was  literally  covered  with  young 
bugs  either  in  the  pupa  stage  or  the  moult  just  preceding,  and  their  advance  was 
southward  toward  the  center  of  the  field.  The  tar  line,  however,  remained  unaf- 
fected, and  proved  the  same  impassable  barrier  to  the  advancing  hosts  as  when  first 
put  down.  A  state  of  utter  confusion  prevailed,  and  the  bugs  ran  restlessly  up  and 
down  the  tar  front,  tumbling  into  the  post-holes,  where  they  were  finally  destroyed, 
or  being  speedily  killed  in  the  furrows  by  the  excessive  heat,  as  they  ran  here  and 
there  over  the  ground. 

The  insects  made  good  their  advance  in  the  eastern  half  of  the  field,  where  no 
barriers  obstructed  their  course,  and  completely  covered  the  corn  as  far  as  the 
ninth  and  tenth  rows  inward.  The  average  yield  in  such  places  was  reported  at  the 
end  of  the  season  by  the  farm  superintendent  as  about  twenty  per  cent,  less  than  that 
of  corresponding  rows  in  the  upper  part  of  the  field,  where  the  barriers  had  been 
used.  The  chinch-bugs,  on  the  other  hand,  were  originally  far  less  numerous  in  this 
part  of  the  wheat  adjacent  than  at  that  end  of  the  field  where  they  were  destroyed 
as  described  above. 

The  five  following  (Nos.  87-91)  are  successive  farmers'  barrier  ex- 
periments made  to  arrest  the  advance  of  chinch-bugs  as  they  moved 
from  wheat  to  corn  in  late  June  and  early  July. 

No.  87.  Made  by  Mr.  Samuel  Bartley,  of  Edgewood  (see  Nos.  63-67),  June  27. 
A  narrow  strip  of  ground  in  corn  along  the  side  adjoining  wheat  (No.  63),  was  deeply 
pulverized,  and  through  this  a  deep  furrow  was  afterwards  made  by  dragging  a  log 
endwise.  The  sides  of  the  furrow  were  as  steep  as  they  could  be  made  without  caving 
in.  The  wheat  was  cut  the  following  day  (June  28),  and  the  chinch-bug  hosts  started 
for  the  corn  field.  Their  advance  was  completely  checked  fora  time,  and  they  accu- 
mulated in  great  numbers  in  the  furrow. 

Mr.  Marten  visited  this  field  June  29.  The  furrow  was  then  in  fair  condition,  and 
contained  myriads  of  bugs  endeavoring  to  escape.  There  were  many  insects  in  the 
wheat  stubble  and  in  a  narrow  strip  of  grass  between  the  wheat  and  corn,  but  com- 
paratively few  on  the  latter  crop. 

No  provision  had  been  made  for  the  destruction  of  the  bugs  in  the  furrow,  and  a 
slight  rain  June  30  breaking  down  the  sides,  in  a  short  time  the  traveling  horde 
made  good  its  escape,  almost  completely  destroying  the  corn  as  it  advanced. 

No.  88.  This  is  a  furrow  experiment,  made  by  Mr.  James  Smith,  of  Farina  (see 
Nos.  59  and  60).  About  June  28,  just  before  wheat  harvest,  Mr.  Smith  abandoned 
his  contagion  box  (No.  59)  and  plowed  furrows  between  wheat  and  corn,  wheat  and 
oats,  and  oats  and  corn.  The  furrows  were  made  about  eight  inches  deep,  with  a 
shovel  plow.  A  log  drawn  by  one  horse  was  dragged  back  and  forth  through  these 
furrows  for  about  a  week.  Myriads  of  bugs  were  crushed,  and  many  died  from  ex- 
posure to  the  heat,  as  they  were  confined  in  the  furrows.  Very  few  bugs  crossed  these 
ditches  into  the  corn,  and  less  than  a  quarter  of  an  acre  was  injured  by  their  attacks. 
A  slight  shower  had  fallen  soon  after  the  log  was  started,  stopping  operations  for 
a  short  time,  and  a  considerable  number  of  chinch-bugs  then  passed  the  furrow,  but 
the  ditches  were  opened  again  as  soon  as  possible,  and  the  dragging  was  resumed. 

At  the  time  of  Mr.  Marten's  visit,  July  n,  the  log  had  not  been  used  for  several 
days,  and  the  bugs  were  crossing  the  ditches  in  great  numbers  and  were  accumulating 
on  the  corn,  where  they  did  considerable  damage  later  in  the  season. 

No.  89.  This  is  a  barrier  experiment  conducted  by  Mr.  C.  M.  Filson  of  Xenia, 
in  corn  (see  No.  80)  adjoining  wheat  which  was  cut  June  15.  The  chinch-bug  horde 
came  into  the  corn  immediately  and  ruined  ten  or  twelve  rows.  Mr.  Filson 


76  BULLETIN    NO.    38.  [Marc/1, 

thoroughly  pulverized  a  narrow  strip  of  ground  in  the  twelfth  row  on  the  south  side 
of  the  field,  and  along  the  outer  edges  of  the  east  and  west  sides,  and  through  this  a 
log  was  dragged  until  a  deep  furrow  was  made  the  entire  length  of  the  three  sides. 
Post-holes  were  then  dug  in  the  furrows  about  ten  feet  apart,  into  which  the  traveling 
bugs  fell  in  great  numbers,  where  they  were  destroyed  with  kerosene  emulsion  or  by 
crushing.  While  the  furrows  were  in  process  of  construction,  quite  a  number  of 
bugs  succeeded  in  crossing  the  ditch  and  accumulated  on  the  first  two  or  three  rows 
beyond.  These  were  destroyed  with  kerosene  emulsion,  applied  by  means  of  a  brush- 
like  broom,  made  of  prairie  grass,  dipped  into  a  pail  containing  the  emulsion  and 
shaken  over  the  bugs  on  each  hill.  Many  insects  fell  on  the  ground  during  this 
operation  and  were  killed  by  the  emulsion.  The  furrows  were  kept  in  good  condition 
for  two  weeks.  The  progress  of  the  incoming  horde  was  practically  arrested,  and 
very  few  bugs  were  seen  in  the  field  the  latter  part  of  the  season.  The  corn  yielded 
about  twenty  bushels  to  the  acre,  which  was  more  than  the  average  for  that  neighbor- 
hood. 

A  field  of  corn,  adjoining  this  same  wheat  field  on  the  south,  in  which  no  meas- 
ures were  taken  to  arrest  and  destroy  the  chinch-bugs  as  they  came  from  the  wheat, 
was  ruined,  excepting  only  a  small  part  which  was  thought  worth  cutting  for  fodder. 

No.  90.  Mr.  H.  H.  Mayo,  of  Falmouth,  in  Jasper  county,  made  a  deep  furrow 
in  a  well-pulverized  strip  of  ground  in  corn.  Wheat  adjoining  was  cut  about  June 
23,  and  the  bugs  entered  the  corn  in  great  numbers.  The  furrow  completely  checked 
their  advance  for  a  time,  and  myriads  of  young  were  seen  dead  in  the  furrow  from 
exposure  to  the  extreme  heat.  A  slight  rain  fell  shortly  after  the  wheat  was  cut, 
after  which  the  furrow  was  not  reconstructed,  and  the  pests  had  free  passageway  into 
the  corn.  Over  four  acres  were  completely  destroyed  in  a  few  days,  and  the  attack 
spread  throughout  the  twenty  acres,  from  which  less  than  half  a  crop  was  taken. 

No.  91.  This  is  a  barrier  experiment  made  by  Mr.  Thos.  B.  Wilson,  Sr.,  of 
Greenup  (see  No.  79),  in  corn  adjoining  wheat.  The  wheat  was  cut  June  25,  and  the 
chinch-bugs  made  rapid  advance  into  the  corn.  The  ground  between  every  fifth  row 
from  the  edge,  for  a  distance  of  twenty  rods,  was  thoroughly  pulverized  and  deeply 
furrowed  June  26.  The  bugs  collected  in  these  furrows  in  great  numbers  and  were 
killed  by  dragging  a  log  back  and  forth.  This  was  kept  up  for  eight  days.  The  first 
fifteen  rows  were  entirely  destroyed,  owing  to  the  fact  that  the  insects  accumulated 
here  before  the  furrows  were  made.  The  corn  in  the  remainder  of  the  field  was  far 
better  than  the  average  in  the  county,  and  yielded  fifty  bushels  to  the  acre. 

In  concluding  this  report,  I  desire  to  express  my  personal  obliga- 
tion and  that  of  the  Station  to  Mr.  John  Marten, by  whom,  as  has  doubt- 
less been  noticed,  by  far  the  greater  part  of  the  detailed  experimental 
work  was  done;  and  to  Mr.  W.  G.  Johnson,  by  whom  the  notes  of  ex- 
periments were  converted  into  the  first  draft  of  the  detailed  descriptions. 

S.  A.  FORBES,  PH.  D.,  Consulting  Entomologist. 


1895-]  EXPERIMENTS    WITH    CHINCH-BUGS.  77 


EXPLANATION  OF  PLATES. 


PLATE  I. 

Farm  of  G.  C.  Wells,  near  Farina,  Fayette  county;  site  of  Experiments  Nos. 
55-58. 

PLATE  II. 

Portion  of  University  Agricultural  Experiment  Station  farm,  at  Urbana,  Illinois, 
showing  the  site  of  Experiments  Nos.  81-86. 

PLATE  III. 

Farm  of  G.  W.  Heth,  near  Edgewood,  Effingham  county;  site  of  Experiment 
No.  77. 

PLATE  IV. 

Farms  of  Silas  Kurd,  and  Frank  H.  Robinson,  near  Odin,  Marion  county;  site 
of  Experiment  No.  75,  and  of  muscardine  outbreak  No.  76. 

PLATE  V. 

Fig.  i.     Mason  fruit-jar  with  altered  cap. 

Fig.  2.     Chinch-bug  imbedded  in  Sporotrichum  bearing  heads  of  ripe  spores. 
Fig.  3.     A   fragment  of    Sporotrichum   from   chinch-bug,    spread   out   to  show 
structure.     Highly  magnified. 

PLATE  VI. 

Culture  mass  of  corn-meal  batter  from  fruit  jar,  covered  with  Sporotrichum, 
showing  its  mode  of  growth  on  solid  media. 

PLATE  VII. 

Isaria  Forms  of  Sporotrichum  giobuliferum,  Speg. 

Fig.  i  and  2.  On  buried  pupae  of  the  apple  leaf  skeletonizer  (Canarsia  hammondi, 
Riley),as  it  appeared  on  the  surface  of  the  ground. 

Fig.  3.     On  pupa  of  same,  the  fungus  bursting  through  the  cocoon. 

Fig.  4.  On  buried  pupa  of  same,  uncovered  and  showing  the  fungus  growth  as 
it  appeared  below  the  surface. 

Fig.  5  and  6.     On  June  beetles  (Lachnosterna)  found  in  ground. 

Fig.  7.  On  pupa  of  walnut  caterpillar  (Datana).  From  laboratory  infection 
experiment. 

Fig.  8.  From  white  grub  dead  under  ground  in  breeding  cage.  From  laboratory 
infection.  The  fungus  immature  and  the  spores  not  yet  fully  formed. 

Fig.  9.  The  same  as  Fig.  8,  but  in  a  later  stage,  the  fungus  being  mature,  and 
the  spores  ripe. 

PLATE  VIII. 

Map  of  Illinois,  showing  area  and  extent  of  distribution  of  muscardine  fungus  in 
1894.  The  figures  for  each  county  indicate  the  number  of  townships  to  which  such 
infection  material  was  distributed  in  June  and  July. 


78 


BULLETIN    NO.    38. 


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PLATE    V.        SPOROTRICHUM    AND    CULTURE    JAR. 


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EXPERIMENTS    WITH    CHINCH-BUGS. 


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BULLETIN    NO.    38. 


[March, 


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PLATE     VII.        ISARIA    FORMS    OF    SPOROTRICHUM. 


EXPERIMENTS    WITH    CHINCH-BUGS. 


PLATE  VIII.        MAP   SHOWING   NUMBER  OF  TOWNSHIPS  IN  EACH  COUNTY 
TO  WHICH   MUSCARDINE   FUNGUS  WAS  SENT   IN  JUNE   AND  JULY. 


86  BULLETIN    NO.    38.  [Marc/t,   1895. 


ORGANIZATION. 


BOARD  OF  TRUSTEES  OF  THE  UNIVERSITY  OF  ILLINOIS. 

NELSON  W.  GRAHAM,  Carbondale,  President. 
JOHN  P.  ALTGELD,  Springfield,  Governor  of  Illinois. 
JAMES  W.  JUDY,   Springfield,  President  State  Board  of  Agriculture. 
SAMUEL  M.  INGLIS,  Springfield,  Superintendent  Public  Instruction. 
RICHARD  P.  MORGAN,  Dwight.  ISAAC  S.  RAYMOND,  Sidney. 

DR.  JULIA  H.  SMITH,  Chicago.  SAMUEL  A.  BULLARD,   Springfield, 

NAPOLEON  B.  MORRISON,  Odin.  ALEXANDER  McLEAN,  Macomb. 

JAMES  E.  ARMSTRONG,  Chicago.  MRS.  LUCY  L.  FLOWER,  Chicago. 

ANDREW  S.   DRAPER,   LL.D.,  President  of  the  University. 

BOARD  OF  DIRECTION  OF  THE  EXPERIMENT  STATION. 

THOMAS  J.  BURRILL,   PH.D.,  Urbana,  Prof,  of  Botany  and  Horticulture,  Pres. 
E.  E.  CHESTER,  Champaign,  of  State  Board  of  Agriculture. 

E.  A.  RIEHL,  Alton,  of  State  Horticultural  Society. 
H.  B.  GURLER,  DeKalb,  of  State  Dairymen's  Association. 

N.  B.  MORRISON,  Odin,  Trustee  of  the  University. 

ISAAC  S.  RAYMOND,  Sidney,  Trustee  of  the  University. 

STEPHEN  A.  FORBES,  PH.D.,  Urbana,  Professor  of  Zoology. 

EUGENE  DAVENPORT,  M.  S  ,  Urbana,  Professor  of  Animal  Husbandry. 

THE  STATION  STAFF. 

THOMAS  J.  BURRILL,  PH.D.,  Horticulturist  and    Botanist,   President  Board    of 

Direction. 

WILLIAM  L.  PILLSBURY,  A.M.,  Urbana,  Secretary. 

EUGENE  DAVENPORT,  M.  S.,  Urbana,   Agriculturist. 

STEPHEN  A.  FORBES,  PH.D.,  Consulting  Entomologist. 

DONALD  McINTOSH,  V.S.,  Consulting  Veterinarian. 
GEORGE  W.  McCLUER,  M.S.,  Assistant  Horticulturist. 

GEORGE  P.  CLINTON,  M.S.,  Assistant  Botanist. 

FRANK  D.  GARDNER,  B.S.,  Assistant  Agriculturist. 

WILL  A.   POWERS,  B.S.,  Assistant  Chemist. 


